diff --git a/.changeset/large-balloons-agree.md b/.changeset/large-balloons-agree.md
new file mode 100644
index 0000000000..9355336862
--- /dev/null
+++ b/.changeset/large-balloons-agree.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: don't show adjusted error messages in boundaries
diff --git a/packages/svelte/src/internal/client/error-handling.js b/packages/svelte/src/internal/client/error-handling.js
index 8e93923c46..a512839181 100644
--- a/packages/svelte/src/internal/client/error-handling.js
+++ b/packages/svelte/src/internal/client/error-handling.js
@@ -66,18 +66,12 @@ export function invoke_error_boundary(error, effect) {
 	throw error;
 }
 
-/** @type {WeakSet<Error>} */
-const adjusted_errors = new WeakSet();
-
 /**
  * Add useful information to the error message/stack in development
  * @param {Error} error
  * @param {Effect} effect
  */
 function get_adjustments(error, effect) {
-	if (adjusted_errors.has(error)) return;
-	adjusted_errors.add(error);
-
 	const message_descriptor = get_descriptor(error, 'message');
 
 	// if the message was already changed and it's not configurable we can't change it
diff --git a/packages/svelte/tests/runtime-runes/samples/error-boundary-3/_config.js b/packages/svelte/tests/runtime-runes/samples/error-boundary-3/_config.js
index 040e13676e..06da8f667c 100644
--- a/packages/svelte/tests/runtime-runes/samples/error-boundary-3/_config.js
+++ b/packages/svelte/tests/runtime-runes/samples/error-boundary-3/_config.js
@@ -9,6 +9,6 @@ export default test({
 		flushSync();
 
 		assert.deepEqual(logs, ['error caught']);
-		assert.htmlEqual(target.innerHTML, `<div>Fallback!</div><button>+</button>`);
+		assert.htmlEqual(target.innerHTML, `<div>oh no!</div><button>+</button>`);
 	}
 });
diff --git a/packages/svelte/tests/runtime-runes/samples/error-boundary-3/main.svelte b/packages/svelte/tests/runtime-runes/samples/error-boundary-3/main.svelte
index bad84666c0..bc7fe072c4 100644
--- a/packages/svelte/tests/runtime-runes/samples/error-boundary-3/main.svelte
+++ b/packages/svelte/tests/runtime-runes/samples/error-boundary-3/main.svelte
@@ -1,6 +1,6 @@
 <script>
 	function throw_error() {
-		throw new Error('test')
+		throw new Error('oh no!')
 	}
 
 	let count = $state(0);
@@ -9,8 +9,8 @@
 <svelte:boundary onerror={(e) => console.log('error caught')}>
 	{count > 0 ? throw_error() : null}
 
-	{#snippet failed()}
-		<div>Fallback!</div>
+	{#snippet failed(e)}
+		<div>{e.message}</div>
 	{/snippet}
 </svelte:boundary>