diff --git a/.changeset/mean-geckos-sell.md b/.changeset/mean-geckos-sell.md
new file mode 100644
index 0000000000..5a72faa07f
--- /dev/null
+++ b/.changeset/mean-geckos-sell.md
@@ -0,0 +1,5 @@
+---
+"astro": patch
+---
+
+Update generator.ts to allow %23 (#) in dynamic urls
diff --git a/packages/astro/src/core/routing/manifest/generator.ts b/packages/astro/src/core/routing/manifest/generator.ts
index 9395a3de2f..c61ce6dca4 100644
--- a/packages/astro/src/core/routing/manifest/generator.ts
+++ b/packages/astro/src/core/routing/manifest/generator.ts
@@ -2,6 +2,25 @@ import type { AstroConfig, RoutePart } from '../../../@types/astro.js';
 
 import { compile } from 'path-to-regexp';
 
+/**
+ * Sanitizes the parameters object by normalizing string values and replacing certain characters with their URL-encoded equivalents.
+ * @param {Record<string, string | number | undefined>} params - The parameters object to be sanitized.
+ * @returns {Record<string, string | number | undefined>} The sanitized parameters object.
+ */
+function sanitizeParams(params: Record<string, string | number | undefined>): Record<string, string | number | undefined> {
+	return Object.fromEntries(
+		Object.entries(params).map(([key, value]) => {
+			if (typeof value === 'string') {
+				return [key, value
+					.normalize()
+					.replace(/#/g, '%23')
+					.replace(/\?/g, '%3F')]
+			}
+			return [key, value];
+		})
+	)
+}
+
 export function getRouteGenerator(
 	segments: RoutePart[][],
 	addTrailingSlash: AstroConfig['trailingSlash']
@@ -37,8 +56,9 @@ export function getRouteGenerator(
 		trailing = '/';
 	}
 	const toPath = compile(template + trailing);
-	return (params: object): string => {
-		const path = toPath(params);
+	return (params: Record<string, string | number | undefined>): string => {
+		const sanitizedParams = sanitizeParams(params);
+		const path = toPath(sanitizedParams);
 
 		// When generating an index from a rest parameter route, `path-to-regexp` will return an
 		// empty string instead "/". This causes an inconsistency with static indexes that may result
diff --git a/packages/astro/test/ssr-params.test.js b/packages/astro/test/ssr-params.test.js
index c5d376fbfc..13c071e7d0 100644
--- a/packages/astro/test/ssr-params.test.js
+++ b/packages/astro/test/ssr-params.test.js
@@ -42,11 +42,11 @@ describe('Astro.params in SSR', () => {
 
 	it('No double URL decoding', async () => {
 		const app = await fixture.loadTestAdapterApp();
-		const request = new Request('http://example.com/users/houston/%25');
+		const request = new Request('http://example.com/users/houston/%25%23%3F');
 		const response = await app.render(request);
 		assert.equal(response.status, 200);
 		const html = await response.text();
 		const $ = cheerio.load(html);
-		assert.equal($('.category').text(), '%');
+		assert.equal($('.category').text(), '%#?');
 	});
 });