diff --git a/documentation/docs/98-reference/.generated/shared-errors.md b/documentation/docs/98-reference/.generated/shared-errors.md
index 4c81d7b89452..6c31aaafd0df 100644
--- a/documentation/docs/98-reference/.generated/shared-errors.md
+++ b/documentation/docs/98-reference/.generated/shared-errors.md
@@ -60,6 +60,43 @@ Certain lifecycle methods can only be used during component initialisation. To f
 <button onclick={handleClick}>click me</button>
 ```
 
+### snippet_without_render_tag
+
+```
+Attempted to render a snippet without a `{@render}` block. This would cause the snippet code to be stringified instead of its content being rendered to the DOM. To fix this, change `{snippet}` to `{@render snippet()}`.
+```
+
+A component throwing this error will look something like this (`children` is not being rendered):
+
+```svelte
+<script>
+    let { children } = $props();
+</script>
+
+{children}
+```
+
+...or like this (a parent component is passing a snippet where a non-snippet value is expected):
+
+```svelte
+<!--- file: Parent.svelte --->
+<ChildComponent>
+  {#snippet label()}
+    <span>Hi!</span>
+  {/snippet}
+</ChildComponent>
+```
+
+```svelte
+<!--- file: Child.svelte --->
+<script>
+  let { label } = $props();
+</script>
+
+<!-- This component doesn't expect a snippet, but the parent provided one -->
+<p>{label}</p>
+```
+
 ### store_invalid_shape
 
 ```
diff --git a/packages/svelte/CHANGELOG.md b/packages/svelte/CHANGELOG.md
index c8f0ad7ed964..4ffcb263abb5 100644
--- a/packages/svelte/CHANGELOG.md
+++ b/packages/svelte/CHANGELOG.md
@@ -1,5 +1,17 @@
 # svelte
 
+## 5.27.1
+
+### Patch Changes
+
+- chore: default params for html blocks ([#15778](https://github.com/sveltejs/svelte/pull/15778))
+
+- fix: correct suggested type for custom events without detail ([#15763](https://github.com/sveltejs/svelte/pull/15763))
+
+- fix: Throw on unrendered snippets in `dev` ([#15766](https://github.com/sveltejs/svelte/pull/15766))
+
+- fix: avoid unnecessary read version increments ([#15777](https://github.com/sveltejs/svelte/pull/15777))
+
 ## 5.27.0
 
 ### Minor Changes
diff --git a/packages/svelte/messages/shared-errors/errors.md b/packages/svelte/messages/shared-errors/errors.md
index 20f3d193d928..4b4d3322028d 100644
--- a/packages/svelte/messages/shared-errors/errors.md
+++ b/packages/svelte/messages/shared-errors/errors.md
@@ -52,6 +52,41 @@ Certain lifecycle methods can only be used during component initialisation. To f
 <button onclick={handleClick}>click me</button>
 ```
 
+## snippet_without_render_tag
+
+> Attempted to render a snippet without a `{@render}` block. This would cause the snippet code to be stringified instead of its content being rendered to the DOM. To fix this, change `{snippet}` to `{@render snippet()}`.
+
+A component throwing this error will look something like this (`children` is not being rendered):
+
+```svelte
+<script>
+    let { children } = $props();
+</script>
+
+{children}
+```
+
+...or like this (a parent component is passing a snippet where a non-snippet value is expected):
+
+```svelte
+<!--- file: Parent.svelte --->
+<ChildComponent>
+  {#snippet label()}
+    <span>Hi!</span>
+  {/snippet}
+</ChildComponent>
+```
+
+```svelte
+<!--- file: Child.svelte --->
+<script>
+  let { label } = $props();
+</script>
+
+<!-- This component doesn't expect a snippet, but the parent provided one -->
+<p>{label}</p>
+```
+
 ## store_invalid_shape
 
 > `%name%` is not a store with a `subscribe` method
diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index af78d2679ab8..7ad4835a9a41 100644
--- a/packages/svelte/package.json
+++ b/packages/svelte/package.json
@@ -2,7 +2,7 @@
   "name": "svelte",
   "description": "Cybernetically enhanced web apps",
   "license": "MIT",
-  "version": "5.27.0",
+  "version": "5.27.1",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/HtmlTag.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/HtmlTag.js
index 32439879de38..ace73691d164 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/HtmlTag.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/HtmlTag.js
@@ -11,17 +11,22 @@ import * as b from '../../../../utils/builders.js';
 export function HtmlTag(node, context) {
 	context.state.template.push('<!>');
 
-	// push into init, so that bindings run afterwards, which might trigger another run and override hydration
-	context.state.init.push(
-		b.stmt(
-			b.call(
-				'$.html',
-				context.state.node,
-				b.thunk(/** @type {Expression} */ (context.visit(node.expression))),
-				b.literal(context.state.metadata.namespace === 'svg'),
-				b.literal(context.state.metadata.namespace === 'mathml'),
-				is_ignored(node, 'hydration_html_changed') && b.true
-			)
+	const expression = /** @type {Expression} */ (context.visit(node.expression));
+
+	const is_svg = context.state.metadata.namespace === 'svg';
+	const is_mathml = context.state.metadata.namespace === 'mathml';
+
+	const statement = b.stmt(
+		b.call(
+			'$.html',
+			context.state.node,
+			b.thunk(expression),
+			is_svg && b.true,
+			is_mathml && b.true,
+			is_ignored(node, 'hydration_html_changed') && b.true
 		)
 	);
+
+	// push into init, so that bindings run afterwards, which might trigger another run and override hydration
+	context.state.init.push(statement);
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/SnippetBlock.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/SnippetBlock.js
index cae3e7d79c94..a67fcc888510 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/SnippetBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/SnippetBlock.js
@@ -1,4 +1,4 @@
-/** @import { BlockStatement } from 'estree' */
+/** @import { ArrowFunctionExpression, BlockStatement, CallExpression } from 'estree' */
 /** @import { AST } from '#compiler' */
 /** @import { ComponentContext } from '../types.js' */
 import { dev } from '../../../../state.js';
@@ -9,20 +9,27 @@ import * as b from '../../../../utils/builders.js';
  * @param {ComponentContext} context
  */
 export function SnippetBlock(node, context) {
-	const fn = b.function_declaration(
-		node.expression,
-		[b.id('$$payload'), ...node.parameters],
-		/** @type {BlockStatement} */ (context.visit(node.body))
-	);
+	const body = /** @type {BlockStatement} */ (context.visit(node.body));
+
 	if (dev) {
-		fn.body.body.unshift(b.stmt(b.call('$.validate_snippet_args', b.id('$$payload'))));
+		body.body.unshift(b.stmt(b.call('$.validate_snippet_args', b.id('$$payload'))));
 	}
+
+	/** @type {ArrowFunctionExpression | CallExpression} */
+	let fn = b.arrow([b.id('$$payload'), ...node.parameters], body);
+
+	if (dev) {
+		fn = b.call('$.prevent_snippet_stringification', fn);
+	}
+
+	const declaration = b.declaration('const', [b.declarator(node.expression, fn)]);
+
 	// @ts-expect-error - TODO remove this hack once $$render_inner for legacy bindings is gone
 	fn.___snippet = true;
 
 	if (node.metadata.can_hoist) {
-		context.state.hoisted.push(fn);
+		context.state.hoisted.push(declaration);
 	} else {
-		context.state.init.push(fn);
+		context.state.init.push(declaration);
 	}
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js
index 695161ff9b60..f4b3dd1b09aa 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js
@@ -4,6 +4,7 @@
 import { empty_comment, build_attribute_value } from './utils.js';
 import * as b from '../../../../../utils/builders.js';
 import { is_element_node } from '../../../../nodes.js';
+import { dev } from '../../../../../state.js';
 
 /**
  * @param {AST.Component | AST.SvelteComponent | AST.SvelteSelf} node
@@ -238,7 +239,13 @@ export function build_inline_component(node, expression, context) {
 				)
 			) {
 				// create `children` prop...
-				push_prop(b.prop('init', b.id('children'), slot_fn));
+				push_prop(
+					b.prop(
+						'init',
+						b.id('children'),
+						dev ? b.call('$.prevent_snippet_stringification', slot_fn) : slot_fn
+					)
+				);
 
 				// and `$$slots.default: true` so that `<slot>` on the child works
 				serialized_slots.push(b.init(slot_name, b.true));
diff --git a/packages/svelte/src/index-client.js b/packages/svelte/src/index-client.js
index fd8e999da763..efd5628ae951 100644
--- a/packages/svelte/src/index-client.js
+++ b/packages/svelte/src/index-client.js
@@ -114,7 +114,7 @@ function create_custom_event(type, detail, { bubbles = false, cancelable = false
  * The event dispatcher can be typed to narrow the allowed event names and the type of the `detail` argument:
  * ```ts
  * const dispatch = createEventDispatcher<{
- *  loaded: never; // does not take a detail argument
+ *  loaded: null; // does not take a detail argument
  *  change: string; // takes a detail argument of type string, which is required
  *  optional: number | null; // takes an optional detail argument of type number
  * }>();
diff --git a/packages/svelte/src/internal/client/dev/debug.js b/packages/svelte/src/internal/client/dev/debug.js
new file mode 100644
index 000000000000..f449dfa2ccd1
--- /dev/null
+++ b/packages/svelte/src/internal/client/dev/debug.js
@@ -0,0 +1,109 @@
+/** @import { Derived, Effect, Value } from '#client' */
+
+import {
+	BLOCK_EFFECT,
+	BOUNDARY_EFFECT,
+	BRANCH_EFFECT,
+	CLEAN,
+	DERIVED,
+	EFFECT,
+	MAYBE_DIRTY,
+	RENDER_EFFECT,
+	ROOT_EFFECT
+} from '../constants.js';
+
+/**
+ *
+ * @param {Effect} effect
+ */
+export function root(effect) {
+	while (effect.parent !== null) {
+		effect = effect.parent;
+	}
+
+	return effect;
+}
+
+/**
+ *
+ * @param {Effect} effect
+ */
+export function log_effect_tree(effect, depth = 0) {
+	const flags = effect.f;
+
+	let label = '(unknown)';
+
+	if ((flags & ROOT_EFFECT) !== 0) {
+		label = 'root';
+	} else if ((flags & BOUNDARY_EFFECT) !== 0) {
+		label = 'boundary';
+	} else if ((flags & BLOCK_EFFECT) !== 0) {
+		label = 'block';
+	} else if ((flags & BRANCH_EFFECT) !== 0) {
+		label = 'branch';
+	} else if ((flags & RENDER_EFFECT) !== 0) {
+		label = 'render effect';
+	} else if ((flags & EFFECT) !== 0) {
+		label = 'effect';
+	}
+
+	let status =
+		(flags & CLEAN) !== 0 ? 'clean' : (flags & MAYBE_DIRTY) !== 0 ? 'maybe dirty' : 'dirty';
+
+	// eslint-disable-next-line no-console
+	console.group(`%c${label} (${status})`, `font-weight: ${status === 'clean' ? 'normal' : 'bold'}`);
+
+	if (depth === 0) {
+		const callsite = new Error().stack
+			?.split('\n')[2]
+			.replace(/\s+at (?: \w+\(?)?(.+)\)?/, (m, $1) => $1.replace(/\?[^:]+/, ''));
+
+		// eslint-disable-next-line no-console
+		console.log(callsite);
+	}
+
+	if (effect.deps !== null) {
+		// eslint-disable-next-line no-console
+		console.groupCollapsed('%cdeps', 'font-weight: normal');
+
+		for (const dep of effect.deps) {
+			log_dep(dep);
+		}
+
+		// eslint-disable-next-line no-console
+		console.groupEnd();
+	}
+
+	let child = effect.first;
+	while (child !== null) {
+		log_effect_tree(child, depth + 1);
+		child = child.next;
+	}
+
+	// eslint-disable-next-line no-console
+	console.groupEnd();
+}
+
+/**
+ *
+ * @param {Value} dep
+ */
+function log_dep(dep) {
+	if ((dep.f & DERIVED) !== 0) {
+		const derived = /** @type {Derived} */ (dep);
+
+		// eslint-disable-next-line no-console
+		console.groupCollapsed('%cderived', 'font-weight: normal', derived.v);
+		if (derived.deps) {
+			for (const d of derived.deps) {
+				log_dep(d);
+			}
+		}
+
+		// eslint-disable-next-line no-console
+		console.groupEnd();
+	} else {
+		// eslint-disable-next-line no-console
+		console.log('state', dep.v);
+	}
+}
diff --git a/packages/svelte/src/internal/client/dom/blocks/html.js b/packages/svelte/src/internal/client/dom/blocks/html.js
index b3fc5a9c725d..92c824347894 100644
--- a/packages/svelte/src/internal/client/dom/blocks/html.js
+++ b/packages/svelte/src/internal/client/dom/blocks/html.js
@@ -1,6 +1,6 @@
 /** @import { Effect, TemplateNode } from '#client' */
 import { FILENAME, HYDRATION_ERROR } from '../../../../constants.js';
-import { block, branch, destroy_effect } from '../../reactivity/effects.js';
+import { remove_effect_dom, template_effect } from '../../reactivity/effects.js';
 import { hydrate_next, hydrate_node, hydrating, set_hydrate_node } from '../hydration.js';
 import { create_fragment_from_html } from '../reconciler.js';
 import { assign_nodes } from '../template.js';
@@ -9,6 +9,7 @@ import { hash, sanitize_location } from '../../../../utils.js';
 import { DEV } from 'esm-env';
 import { dev_current_component_function } from '../../context.js';
 import { get_first_child, get_next_sibling } from '../operations.js';
+import { active_effect } from '../../runtime.js';
 
 /**
  * @param {Element} element
@@ -34,89 +35,81 @@ function check_hash(element, server_hash, value) {
 /**
  * @param {Element | Text | Comment} node
  * @param {() => string} get_value
- * @param {boolean} svg
- * @param {boolean} mathml
+ * @param {boolean} [svg]
+ * @param {boolean} [mathml]
  * @param {boolean} [skip_warning]
  * @returns {void}
  */
-export function html(node, get_value, svg, mathml, skip_warning) {
+export function html(node, get_value, svg = false, mathml = false, skip_warning = false) {
 	var anchor = node;
 
 	var value = '';
 
-	/** @type {Effect | undefined} */
-	var effect;
+	template_effect(() => {
+		var effect = /** @type {Effect} */ (active_effect);
 
-	block(() => {
 		if (value === (value = get_value() ?? '')) {
-			if (hydrating) {
-				hydrate_next();
-			}
+			if (hydrating) hydrate_next();
 			return;
 		}
 
-		if (effect !== undefined) {
-			destroy_effect(effect);
-			effect = undefined;
+		if (effect.nodes_start !== null) {
+			remove_effect_dom(effect.nodes_start, /** @type {TemplateNode} */ (effect.nodes_end));
+			effect.nodes_start = effect.nodes_end = null;
 		}
 
 		if (value === '') return;
 
-		effect = branch(() => {
-			if (hydrating) {
-				// We're deliberately not trying to repair mismatches between server and client,
-				// as it's costly and error-prone (and it's an edge case to have a mismatch anyway)
-				var hash = /** @type {Comment} */ (hydrate_node).data;
-				var next = hydrate_next();
-				var last = next;
-
-				while (
-					next !== null &&
-					(next.nodeType !== 8 || /** @type {Comment} */ (next).data !== '')
-				) {
-					last = next;
-					next = /** @type {TemplateNode} */ (get_next_sibling(next));
-				}
-
-				if (next === null) {
-					w.hydration_mismatch();
-					throw HYDRATION_ERROR;
-				}
-
-				if (DEV && !skip_warning) {
-					check_hash(/** @type {Element} */ (next.parentNode), hash, value);
-				}
-
-				assign_nodes(hydrate_node, last);
-				anchor = set_hydrate_node(next);
-				return;
-			}
+		if (hydrating) {
+			// We're deliberately not trying to repair mismatches between server and client,
+			// as it's costly and error-prone (and it's an edge case to have a mismatch anyway)
+			var hash = /** @type {Comment} */ (hydrate_node).data;
+			var next = hydrate_next();
+			var last = next;
 
-			var html = value + '';
-			if (svg) html = `<svg>${html}</svg>`;
-			else if (mathml) html = `<math>${html}</math>`;
+			while (next !== null && (next.nodeType !== 8 || /** @type {Comment} */ (next).data !== '')) {
+				last = next;
+				next = /** @type {TemplateNode} */ (get_next_sibling(next));
+			}
 
-			// Don't use create_fragment_with_script_from_html here because that would mean script tags are executed.
-			// @html is basically `.innerHTML = ...` and that doesn't execute scripts either due to security reasons.
-			/** @type {DocumentFragment | Element} */
-			var node = create_fragment_from_html(html);
+			if (next === null) {
+				w.hydration_mismatch();
+				throw HYDRATION_ERROR;
+			}
 
-			if (svg || mathml) {
-				node = /** @type {Element} */ (get_first_child(node));
+			if (DEV && !skip_warning) {
+				check_hash(/** @type {Element} */ (next.parentNode), hash, value);
 			}
 
-			assign_nodes(
-				/** @type {TemplateNode} */ (get_first_child(node)),
-				/** @type {TemplateNode} */ (node.lastChild)
-			);
-
-			if (svg || mathml) {
-				while (get_first_child(node)) {
-					anchor.before(/** @type {Node} */ (get_first_child(node)));
-				}
-			} else {
-				anchor.before(node);
+			assign_nodes(hydrate_node, last);
+			anchor = set_hydrate_node(next);
+			return;
+		}
+
+		var html = value + '';
+		if (svg) html = `<svg>${html}</svg>`;
+		else if (mathml) html = `<math>${html}</math>`;
+
+		// Don't use create_fragment_with_script_from_html here because that would mean script tags are executed.
+		// @html is basically `.innerHTML = ...` and that doesn't execute scripts either due to security reasons.
+		/** @type {DocumentFragment | Element} */
+		var node = create_fragment_from_html(html);
+
+		if (svg || mathml) {
+			node = /** @type {Element} */ (get_first_child(node));
+		}
+
+		assign_nodes(
+			/** @type {TemplateNode} */ (get_first_child(node)),
+			/** @type {TemplateNode} */ (node.lastChild)
+		);
+
+		if (svg || mathml) {
+			while (get_first_child(node)) {
+				anchor.before(/** @type {Node} */ (get_first_child(node)));
 			}
-		});
+		} else {
+			anchor.before(node);
+		}
 	});
 }
diff --git a/packages/svelte/src/internal/client/dom/blocks/snippet.js b/packages/svelte/src/internal/client/dom/blocks/snippet.js
index b916a02ce55f..a48153900fde 100644
--- a/packages/svelte/src/internal/client/dom/blocks/snippet.js
+++ b/packages/svelte/src/internal/client/dom/blocks/snippet.js
@@ -15,6 +15,7 @@ import * as e from '../../errors.js';
 import { DEV } from 'esm-env';
 import { get_first_child, get_next_sibling } from '../operations.js';
 import { noop } from '../../../shared/utils.js';
+import { prevent_snippet_stringification } from '../../../shared/validate.js';
 
 /**
  * @template {(node: TemplateNode, ...args: any[]) => void} SnippetFn
@@ -60,7 +61,7 @@ export function snippet(node, get_snippet, ...args) {
  * @param {(node: TemplateNode, ...args: any[]) => void} fn
  */
 export function wrap_snippet(component, fn) {
-	return (/** @type {TemplateNode} */ node, /** @type {any[]} */ ...args) => {
+	const snippet = (/** @type {TemplateNode} */ node, /** @type {any[]} */ ...args) => {
 		var previous_component_function = dev_current_component_function;
 		set_dev_current_component_function(component);
 
@@ -70,6 +71,10 @@ export function wrap_snippet(component, fn) {
 			set_dev_current_component_function(previous_component_function);
 		}
 	};
+
+	prevent_snippet_stringification(snippet);
+
+	return snippet;
 }
 
 /**
diff --git a/packages/svelte/src/internal/client/index.js b/packages/svelte/src/internal/client/index.js
index e977bf3b0fe9..14d6e29f5bb4 100644
--- a/packages/svelte/src/internal/client/index.js
+++ b/packages/svelte/src/internal/client/index.js
@@ -157,7 +157,8 @@ export {
 	invalid_default_snippet,
 	validate_dynamic_element_tag,
 	validate_store,
-	validate_void_dynamic_element
+	validate_void_dynamic_element,
+	prevent_snippet_stringification
 } from '../shared/validate.js';
 export { strict_equals, equals } from './dev/equality.js';
 export { log_if_contains_state } from './dev/console-log.js';
diff --git a/packages/svelte/src/internal/client/reactivity/effects.js b/packages/svelte/src/internal/client/reactivity/effects.js
index 468bb94ab428..76b014c916c6 100644
--- a/packages/svelte/src/internal/client/reactivity/effects.js
+++ b/packages/svelte/src/internal/client/reactivity/effects.js
@@ -427,18 +427,7 @@ export function destroy_effect(effect, remove_dom = true) {
 	var removed = false;
 
 	if ((remove_dom || (effect.f & HEAD_EFFECT) !== 0) && effect.nodes_start !== null) {
-		/** @type {TemplateNode | null} */
-		var node = effect.nodes_start;
-		var end = effect.nodes_end;
-
-		while (node !== null) {
-			/** @type {TemplateNode | null} */
-			var next = node === end ? null : /** @type {TemplateNode} */ (get_next_sibling(node));
-
-			node.remove();
-			node = next;
-		}
-
+		remove_effect_dom(effect.nodes_start, /** @type {TemplateNode} */ (effect.nodes_end));
 		removed = true;
 	}
 
@@ -480,6 +469,21 @@ export function destroy_effect(effect, remove_dom = true) {
 			null;
 }
 
+/**
+ *
+ * @param {TemplateNode | null} node
+ * @param {TemplateNode} end
+ */
+export function remove_effect_dom(node, end) {
+	while (node !== null) {
+		/** @type {TemplateNode | null} */
+		var next = node === end ? null : /** @type {TemplateNode} */ (get_next_sibling(node));
+
+		node.remove();
+		node = next;
+	}
+}
+
 /**
  * Detach an effect from the effect tree, freeing up memory and
  * reducing the amount of work that happens on subsequent traversals
diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
index 2acad3d2580d..e621536055b5 100644
--- a/packages/svelte/src/internal/client/runtime.js
+++ b/packages/svelte/src/internal/client/runtime.js
@@ -469,7 +469,7 @@ export function update_reaction(reaction) {
 		// we need to increment the read version to ensure that
 		// any dependencies in this reaction aren't marked with
 		// the same version
-		if (previous_reaction !== reaction) {
+		if (previous_reaction !== null && previous_reaction !== reaction) {
 			read_version++;
 
 			if (untracked_writes !== null) {
diff --git a/packages/svelte/src/internal/server/index.js b/packages/svelte/src/internal/server/index.js
index d711778a44ea..b58a1d4372a6 100644
--- a/packages/svelte/src/internal/server/index.js
+++ b/packages/svelte/src/internal/server/index.js
@@ -509,7 +509,8 @@ export { fallback } from '../shared/utils.js';
 export {
 	invalid_default_snippet,
 	validate_dynamic_element_tag,
-	validate_void_dynamic_element
+	validate_void_dynamic_element,
+	prevent_snippet_stringification
 } from '../shared/validate.js';
 
 export { escape_html as escape };
diff --git a/packages/svelte/src/internal/shared/errors.js b/packages/svelte/src/internal/shared/errors.js
index 2e89dc1ad109..b8606fbf6f7d 100644
--- a/packages/svelte/src/internal/shared/errors.js
+++ b/packages/svelte/src/internal/shared/errors.js
@@ -48,6 +48,21 @@ export function lifecycle_outside_component(name) {
 	}
 }
 
+/**
+ * Attempted to render a snippet without a `{@render}` block. This would cause the snippet code to be stringified instead of its content being rendered to the DOM. To fix this, change `{snippet}` to `{@render snippet()}`.
+ * @returns {never}
+ */
+export function snippet_without_render_tag() {
+	if (DEV) {
+		const error = new Error(`snippet_without_render_tag\nAttempted to render a snippet without a \`{@render}\` block. This would cause the snippet code to be stringified instead of its content being rendered to the DOM. To fix this, change \`{snippet}\` to \`{@render snippet()}\`.\nhttps://svelte.dev/e/snippet_without_render_tag`);
+
+		error.name = 'Svelte error';
+		throw error;
+	} else {
+		throw new Error(`https://svelte.dev/e/snippet_without_render_tag`);
+	}
+}
+
 /**
  * `%name%` is not a store with a `subscribe` method
  * @param {string} name
diff --git a/packages/svelte/src/internal/shared/validate.js b/packages/svelte/src/internal/shared/validate.js
index 852c0e83bfb1..bbb237594bec 100644
--- a/packages/svelte/src/internal/shared/validate.js
+++ b/packages/svelte/src/internal/shared/validate.js
@@ -35,3 +35,15 @@ export function validate_store(store, name) {
 		e.store_invalid_shape(name);
 	}
 }
+
+/**
+ * @template {() => unknown} T
+ * @param {T} fn
+ */
+export function prevent_snippet_stringification(fn) {
+	fn.toString = () => {
+		e.snippet_without_render_tag();
+		return '';
+	};
+	return fn;
+}
diff --git a/packages/svelte/src/version.js b/packages/svelte/src/version.js
index 27a39136f8c2..b0424e82325a 100644
--- a/packages/svelte/src/version.js
+++ b/packages/svelte/src/version.js
@@ -4,5 +4,5 @@
  * The current version, as set in package.json.
  * @type {string}
  */
-export const VERSION = '5.27.0';
+export const VERSION = '5.27.1';
 export const PUBLIC_VERSION = '5';
diff --git a/packages/svelte/tests/runtime-runes/samples/snippet-block-without-render-tag-dev/_config.js b/packages/svelte/tests/runtime-runes/samples/snippet-block-without-render-tag-dev/_config.js
new file mode 100644
index 000000000000..94c5de10af60
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/snippet-block-without-render-tag-dev/_config.js
@@ -0,0 +1,8 @@
+import { test } from '../../test';
+
+export default test({
+	compileOptions: {
+		dev: true
+	},
+	runtime_error: 'snippet_without_render_tag'
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/snippet-block-without-render-tag-dev/main.svelte b/packages/svelte/tests/runtime-runes/samples/snippet-block-without-render-tag-dev/main.svelte
new file mode 100644
index 000000000000..3f8edfe4fafc
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/snippet-block-without-render-tag-dev/main.svelte
@@ -0,0 +1,5 @@
+{testSnippet}
+
+{#snippet testSnippet()}
+  <p>hi again</p>
+{/snippet}
diff --git a/packages/svelte/tests/runtime-runes/samples/snippet-block-without-render-tag-prod/_config.js b/packages/svelte/tests/runtime-runes/samples/snippet-block-without-render-tag-prod/_config.js
new file mode 100644
index 000000000000..f47bee71df87
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/snippet-block-without-render-tag-prod/_config.js
@@ -0,0 +1,3 @@
+import { test } from '../../test';
+
+export default test({});
diff --git a/packages/svelte/tests/runtime-runes/samples/snippet-block-without-render-tag-prod/main.svelte b/packages/svelte/tests/runtime-runes/samples/snippet-block-without-render-tag-prod/main.svelte
new file mode 100644
index 000000000000..3f8edfe4fafc
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/snippet-block-without-render-tag-prod/main.svelte
@@ -0,0 +1,5 @@
+{testSnippet}
+
+{#snippet testSnippet()}
+  <p>hi again</p>
+{/snippet}
diff --git a/packages/svelte/tests/runtime-runes/samples/snippet-children-without-render-tag-dev-prod/_config.js b/packages/svelte/tests/runtime-runes/samples/snippet-children-without-render-tag-dev-prod/_config.js
new file mode 100644
index 000000000000..f47bee71df87
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/snippet-children-without-render-tag-dev-prod/_config.js
@@ -0,0 +1,3 @@
+import { test } from '../../test';
+
+export default test({});
diff --git a/packages/svelte/tests/runtime-runes/samples/snippet-children-without-render-tag-dev-prod/main.svelte b/packages/svelte/tests/runtime-runes/samples/snippet-children-without-render-tag-dev-prod/main.svelte
new file mode 100644
index 000000000000..4a4ed3176f24
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/snippet-children-without-render-tag-dev-prod/main.svelte
@@ -0,0 +1,5 @@
+<script>
+  import UnrenderedChildren from './unrendered-children.svelte';
+</script>
+
+<UnrenderedChildren>Hi</UnrenderedChildren>
diff --git a/packages/svelte/tests/runtime-runes/samples/snippet-children-without-render-tag-dev-prod/unrendered-children.svelte b/packages/svelte/tests/runtime-runes/samples/snippet-children-without-render-tag-dev-prod/unrendered-children.svelte
new file mode 100644
index 000000000000..6b7154a5a406
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/snippet-children-without-render-tag-dev-prod/unrendered-children.svelte
@@ -0,0 +1,5 @@
+<script>
+  let { children } = $props();
+</script>
+
+{children}
diff --git a/packages/svelte/tests/runtime-runes/samples/snippet-children-without-render-tag-dev/_config.js b/packages/svelte/tests/runtime-runes/samples/snippet-children-without-render-tag-dev/_config.js
new file mode 100644
index 000000000000..94c5de10af60
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/snippet-children-without-render-tag-dev/_config.js
@@ -0,0 +1,8 @@
+import { test } from '../../test';
+
+export default test({
+	compileOptions: {
+		dev: true
+	},
+	runtime_error: 'snippet_without_render_tag'
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/snippet-children-without-render-tag-dev/main.svelte b/packages/svelte/tests/runtime-runes/samples/snippet-children-without-render-tag-dev/main.svelte
new file mode 100644
index 000000000000..4a4ed3176f24
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/snippet-children-without-render-tag-dev/main.svelte
@@ -0,0 +1,5 @@
+<script>
+  import UnrenderedChildren from './unrendered-children.svelte';
+</script>
+
+<UnrenderedChildren>Hi</UnrenderedChildren>
diff --git a/packages/svelte/tests/runtime-runes/samples/snippet-children-without-render-tag-dev/unrendered-children.svelte b/packages/svelte/tests/runtime-runes/samples/snippet-children-without-render-tag-dev/unrendered-children.svelte
new file mode 100644
index 000000000000..6b7154a5a406
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/snippet-children-without-render-tag-dev/unrendered-children.svelte
@@ -0,0 +1,5 @@
+<script>
+  let { children } = $props();
+</script>
+
+{children}
diff --git a/packages/svelte/tests/snapshot/samples/bind-component-snippet/_expected/server/index.svelte.js b/packages/svelte/tests/snapshot/samples/bind-component-snippet/_expected/server/index.svelte.js
index cadae2cf15c0..04bfbf6ae47b 100644
--- a/packages/svelte/tests/snapshot/samples/bind-component-snippet/_expected/server/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/bind-component-snippet/_expected/server/index.svelte.js
@@ -1,9 +1,9 @@
 import * as $ from 'svelte/internal/server';
 import TextInput from './Child.svelte';
 
-function snippet($$payload) {
+const snippet = ($$payload) => {
 	$$payload.out += `<!---->Something`;
-}
+};
 
 export default function Bind_component_snippet($$payload) {
 	let value = '';
diff --git a/packages/svelte/tests/snapshot/samples/skip-static-subtree/_expected/client/index.svelte.js b/packages/svelte/tests/snapshot/samples/skip-static-subtree/_expected/client/index.svelte.js
index b341d39f28fb..541b56a407ba 100644
--- a/packages/svelte/tests/snapshot/samples/skip-static-subtree/_expected/client/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/skip-static-subtree/_expected/client/index.svelte.js
@@ -13,7 +13,7 @@ export default function Skip_static_subtree($$anchor, $$props) {
 
 	var node = $.sibling(h1, 10);
 
-	$.html(node, () => $$props.content, false, false);
+	$.html(node, () => $$props.content);
 	$.next(14);
 	$.reset(main);
 
diff --git a/packages/svelte/types/index.d.ts b/packages/svelte/types/index.d.ts
index 6f12daf18778..8fc174b0a944 100644
--- a/packages/svelte/types/index.d.ts
+++ b/packages/svelte/types/index.d.ts
@@ -381,7 +381,7 @@ declare module 'svelte' {
 	 * The event dispatcher can be typed to narrow the allowed event names and the type of the `detail` argument:
 	 * ```ts
 	 * const dispatch = createEventDispatcher<{
-	 *  loaded: never; // does not take a detail argument
+	 *  loaded: null; // does not take a detail argument
 	 *  change: string; // takes a detail argument of type string, which is required
 	 *  optional: number | null; // takes an optional detail argument of type number
 	 * }>();

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