diff --git a/server/index.ts b/server/index.ts
index 5caed72cb..874cd57f1 100644
--- a/server/index.ts
+++ b/server/index.ts
@@ -87,11 +87,17 @@ const getHost = (req: { get: (key: string) => string | undefined }) =>
 
 const MODE = process.env.NODE_ENV
 
-if (MODE === 'production' && process.env.SENTRY_DSN) {
+const SHOULD_INIT_SENTRY =
+	MODE === 'production' &&
+	Boolean(process.env.SENTRY_DSN) &&
+	// `start:mocks` (used in CI + local e2e) runs with `MOCKS=true`.
+	process.env.MOCKS !== 'true'
+
+if (SHOULD_INIT_SENTRY) {
 	void import('./utils/monitoring.js').then(({ init }) => init())
 }
 
-if (MODE === 'production') {
+if (SHOULD_INIT_SENTRY) {
 	sentryInit({
 		dsn: process.env.SENTRY_DSN,
 		tracesSampleRate: 0.3,
diff --git a/vite.config.ts b/vite.config.ts
index 040b8b91e..e6ec0e741 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -2,13 +2,36 @@ import 'dotenv/config'
 import { reactRouter } from '@react-router/dev/vite'
 import { sentryVitePlugin } from '@sentry/vite-plugin'
 import tailwindcss from '@tailwindcss/vite'
-import { glob } from 'glob'
 import { defineConfig } from 'vite'
 import { envOnlyMacros } from 'vite-env-only'
 import { cjsInterop } from 'vite-plugin-cjs-interop'
 import tsconfigPaths from 'vite-tsconfig-paths'
 
 const MODE = process.env.NODE_ENV
+const SENTRY_UPLOAD =
+	process.env.SENTRY_UPLOAD === 'true' || process.env.SENTRY_UPLOAD === '1'
+
+if (SENTRY_UPLOAD && MODE === 'production') {
+	const authToken = process.env.SENTRY_AUTH_TOKEN
+	const project = process.env.SENTRY_PROJECT
+	const org = process.env.SENTRY_ORG
+	// New-style Sentry auth tokens (prefix "sntrys_") embed the org, so SENTRY_ORG
+	// is not required when using one.
+	const tokenImpliesOrg = Boolean(authToken?.startsWith('sntrys_'))
+
+	// If upload is "on" but required settings are missing, the Sentry plugin will
+	// just warn + skip the upload. Fail fast so we don't silently deploy without
+	// sourcemaps in Sentry.
+	if (!authToken) {
+		throw new Error('SENTRY_UPLOAD is enabled, but SENTRY_AUTH_TOKEN is missing')
+	}
+	if (!project) {
+		throw new Error('SENTRY_UPLOAD is enabled, but SENTRY_PROJECT is missing')
+	}
+	if (!org && !tokenImpliesOrg) {
+		throw new Error('SENTRY_UPLOAD is enabled, but SENTRY_ORG is missing')
+	}
+}
 
 export default defineConfig(async () => {
 	return {
@@ -24,28 +47,31 @@ export default defineConfig(async () => {
 			tailwindcss(),
 			reactRouter(),
 			tsconfigPaths(),
-			process.env.SENTRY_UPLOAD
+			SENTRY_UPLOAD
 				? sentryVitePlugin({
 						disable: MODE !== 'production',
 						authToken: process.env.SENTRY_AUTH_TOKEN,
 						org: process.env.SENTRY_ORG,
 						project: process.env.SENTRY_PROJECT,
+						// By default the bundler plugin logs and continues on upload/release
+						// errors. Fail the build so we don't deploy with broken symbolication.
+						errorHandler: (err) => {
+							throw err
+						},
 						release: {
 							name: process.env.COMMIT_SHA,
 							setCommits: {
 								auto: true,
 							},
 						},
-						sourcemaps: {
-							filesToDeleteAfterUpload: await glob([
-								'./build/**/*.map',
-								'.server-build/**/*.map',
-							]),
-						},
 					})
 				: null,
 		],
 		build: {
+			// This is an OSS project, so it's fine to generate "regular" sourcemaps.
+			// If we ever want sourcemaps upload without exposing them publicly, switch
+			// to `sourcemap: 'hidden'` (and keep uploading to Sentry).
+			sourcemap: true,
 			cssMinify: MODE === 'production',
 			rollupOptions: {
 				external: [/node:.*/, 'stream', 'crypto'],