diff --git a/backend/src/handlers/me.rs b/backend/src/handlers/me.rs
index 71c1df1..79ecd88 100644
--- a/backend/src/handlers/me.rs
+++ b/backend/src/handlers/me.rs
@@ -55,6 +55,9 @@ pub struct MeContextDto {
     pub privacy_note: String,
     pub quota_enabled: bool,
     pub storage_quota_enabled: bool,
+    /// Whether uploads are currently locked for the event, so the client can show
+    /// a banner + disable the upload affordance on load (not just via SSE).
+    pub uploads_locked: bool,
 }
 
 pub async fn get_context(
@@ -68,6 +71,10 @@ pub async fn get_context(
     let privacy_note = config::get_str(&state.pool, "privacy_note", "").await;
     let quota_enabled = config::get_bool(&state.pool, "quota_enabled", true).await;
     let storage_quota_enabled = config::get_bool(&state.pool, "storage_quota_enabled", true).await;
+    let uploads_locked = crate::models::event::Event::find_by_slug(&state.pool, &state.config.event_slug)
+        .await?
+        .map(|e| e.uploads_locked_at.is_some())
+        .unwrap_or(false);
 
     Ok(Json(MeContextDto {
         user_id: user.id,
@@ -76,5 +83,6 @@ pub async fn get_context(
         privacy_note,
         quota_enabled,
         storage_quota_enabled,
+        uploads_locked,
     }))
 }
diff --git a/frontend/src/lib/api.ts b/frontend/src/lib/api.ts
index 2ac3b4b..1d90d9c 100644
--- a/frontend/src/lib/api.ts
+++ b/frontend/src/lib/api.ts
@@ -1,3 +1,5 @@
+import { goto } from '$app/navigation';
+import { browser } from '$app/environment';
 import { getToken, clearAuth } from './auth';
 
 const BASE = '/api/v1';
@@ -42,6 +44,11 @@ async function request<T>(
 	if (!res.ok) {
 		if (res.status === 401) {
 			clearAuth();
+			// Don't strand the user on a now-unauthenticated page with no nav —
+			// send them to /join. Guard against loops on the auth screens.
+			if (browser && !/^\/(join|recover|admin\/login)/.test(window.location.pathname)) {
+				void goto('/join');
+			}
 		}
 		throw new ApiError(res.status, data.error ?? 'unknown', data.message ?? 'Fehler');
 	}
diff --git a/frontend/src/lib/components/BottomNav.svelte b/frontend/src/lib/components/BottomNav.svelte
index e92f6b5..b6389f7 100644
--- a/frontend/src/lib/components/BottomNav.svelte
+++ b/frontend/src/lib/components/BottomNav.svelte
@@ -3,6 +3,7 @@
 	import { page } from '$app/stores';
 	import { uploadSheetOpen, uploadBadgeCount } from '$lib/ui-store';
 	import { exportStatus, initExportStatus } from '$lib/export-status-store';
+	import { uploadsLocked } from '$lib/event-state-store';
 
 	function isActive(path: string): boolean {
 		return $page.url.pathname.startsWith(path);
@@ -43,8 +44,9 @@
 		<div class="relative -translate-y-3">
 			<button
 				onclick={() => ($uploadSheetOpen = true)}
-				class="relative flex h-14 w-14 items-center justify-center rounded-full bg-blue-600 text-white shadow-lg transition active:scale-95 hover:bg-blue-700"
-				aria-label="Hochladen"
+				disabled={$uploadsLocked}
+				class="relative flex h-14 w-14 items-center justify-center rounded-full bg-blue-600 text-white shadow-lg transition active:scale-95 hover:bg-blue-700 disabled:cursor-not-allowed disabled:opacity-40 disabled:hover:bg-blue-600 disabled:active:scale-100"
+				aria-label={$uploadsLocked ? 'Uploads gesperrt' : 'Hochladen'}
 			>
 				<!-- Camera + plus icon -->
 				<svg class="h-6 w-6" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="1.5">
diff --git a/frontend/src/lib/components/UploadSheet.svelte b/frontend/src/lib/components/UploadSheet.svelte
index 4158e7d..70f75ef 100644
--- a/frontend/src/lib/components/UploadSheet.svelte
+++ b/frontend/src/lib/components/UploadSheet.svelte
@@ -7,6 +7,8 @@
 
 	let showCamera = $state(false);
 	let fileInput: HTMLInputElement;
+	let sheet = $state<HTMLDivElement | null>(null);
+	let returnFocus: HTMLElement | null = null;
 
 	// Keep the sheet and backdrop always in the DOM for smooth CSS transitions.
 	let open = $derived($uploadSheetOpen);
@@ -15,6 +17,50 @@
 		uploadSheetOpen.set(false);
 	}
 
+	// Modal contract (mirrors ContextSheet): trap Tab within the sheet, close on
+	// Escape, and restore focus on close. The sheet is permanently mounted (CSS
+	// translate animation), so this is wired via $effect — and `inert`/`aria-hidden`
+	// below keep its controls out of the tab order + AT tree while closed.
+	function onKeyDown(e: KeyboardEvent) {
+		if (e.key === 'Escape') {
+			e.preventDefault();
+			close();
+			return;
+		}
+		if (e.key !== 'Tab' || !sheet) return;
+		const list = Array.from(sheet.querySelectorAll<HTMLElement>('button:not([disabled])'));
+		if (list.length === 0) return;
+		const first = list[0];
+		const last = list[list.length - 1];
+		const active = document.activeElement as HTMLElement | null;
+		if (e.shiftKey && (active === first || !sheet.contains(active))) {
+			e.preventDefault();
+			last.focus();
+		} else if (!e.shiftKey && active === last) {
+			e.preventDefault();
+			first.focus();
+		}
+	}
+
+	$effect(() => {
+		if (open) {
+			returnFocus = (document.activeElement as HTMLElement | null) ?? null;
+			requestAnimationFrame(() => {
+				const first = sheet?.querySelector<HTMLButtonElement>('button:not([disabled])');
+				first?.focus({ preventScroll: true });
+			});
+			window.addEventListener('keydown', onKeyDown);
+			return () => window.removeEventListener('keydown', onKeyDown);
+		} else if (returnFocus) {
+			try {
+				returnFocus.focus({ preventScroll: true });
+			} catch {
+				/* element gone */
+			}
+			returnFocus = null;
+		}
+	});
+
 	function openGallery() {
 		fileInput?.click();
 	}
@@ -80,10 +126,17 @@
 
 <!-- Sheet -->
 <div
+	bind:this={sheet}
 	class="fixed inset-x-0 bottom-0 z-50 rounded-t-2xl bg-white transition-transform duration-300 dark:bg-gray-900"
 	class:translate-y-full={!open}
 	class:translate-y-0={open}
+	class:pointer-events-none={!open}
 	style="padding-bottom: env(safe-area-inset-bottom)"
+	role="dialog"
+	aria-modal="true"
+	aria-label="Hochladen"
+	tabindex="-1"
+	inert={!open}
 >
 	<!-- Drag handle -->
 	<div class="flex justify-center pt-3 pb-1">
diff --git a/frontend/src/lib/event-state-store.ts b/frontend/src/lib/event-state-store.ts
new file mode 100644
index 0000000..923ae30
--- /dev/null
+++ b/frontend/src/lib/event-state-store.ts
@@ -0,0 +1,10 @@
+// Shared, reactive event state pushed from the backend.
+//
+// `uploadsLocked` is seeded from `/me/context` on boot and kept live by the
+// `event-closed` / `event-opened` SSE events (wired in the root layout). Pages
+// read it to show an "Uploads gesperrt" banner and disable the upload FAB, so a
+// locked event stops inviting uploads that would only fail server-side.
+
+import { writable } from 'svelte/store';
+
+export const uploadsLocked = writable<boolean>(false);
diff --git a/frontend/src/lib/types.ts b/frontend/src/lib/types.ts
index b198551..5187769 100644
--- a/frontend/src/lib/types.ts
+++ b/frontend/src/lib/types.ts
@@ -55,6 +55,7 @@ export interface MeContextDto {
 	privacy_note: string;
 	quota_enabled: boolean;
 	storage_quota_enabled: boolean;
+	uploads_locked: boolean;
 }
 
 // mirrors backend/src/handlers/host.rs::PinResetResponse
diff --git a/frontend/src/routes/+layout.svelte b/frontend/src/routes/+layout.svelte
index 52bdbde..14f356a 100644
--- a/frontend/src/routes/+layout.svelte
+++ b/frontend/src/routes/+layout.svelte
@@ -1,8 +1,9 @@
 <script lang="ts">
 	import favicon from '$lib/assets/favicon.svg';
 	import '../app.css';
-	import { initAuth, getToken, getUserId, clearPin } from '$lib/auth';
+	import { initAuth, getToken, getUserId, clearPin, clearAuth } from '$lib/auth';
 	import { initTheme } from '$lib/theme-store';
+	import { goto } from '$app/navigation';
 	import { onMount, onDestroy } from 'svelte';
 	import BottomNav from '$lib/components/BottomNav.svelte';
 	import UploadSheet from '$lib/components/UploadSheet.svelte';
@@ -14,12 +15,28 @@
 	import { refreshQuota } from '$lib/quota-store';
 	import { onSseEvent } from '$lib/sse';
 	import { api } from '$lib/api';
+	import { toast } from '$lib/toast-store';
+	import { uploadsLocked } from '$lib/event-state-store';
 	import type { MeContextDto } from '$lib/types';
 
 	let { children } = $props();
 
 	let unsubs: Array<() => void> = [];
 
+	// H12: surface upload failures. The queue marks failed items 'error' in
+	// IndexedDB but nothing rendered them, so a banned/locked/over-quota guest saw
+	// the composer close to a normal feed and assumed success. Toast each item the
+	// first time it transitions to 'error'.
+	let toastedErrors = new Set<string>();
+	$effect(() => {
+		for (const item of $queueItems) {
+			if (item.status === 'error' && !toastedErrors.has(item.id)) {
+				toastedErrors.add(item.id);
+				toast(item.error ?? 'Upload fehlgeschlagen.', 'error');
+			}
+		}
+	});
+
 	// Slim progress bar: ratio of completed items to total, shown while processing.
 	let progressPct = $derived.by(() => {
 		const total = $queueItems.length;
@@ -39,6 +56,7 @@
 			try {
 				const ctx = await api.get<MeContextDto>('/me/context');
 				privacyNote.set(ctx.privacy_note);
+				uploadsLocked.set(ctx.uploads_locked);
 			} catch {
 				// Cross-cutting hydration on boot — failure is non-fatal; users without
 				// a session land on /join anyway, and the per-page mount will retry.
@@ -61,7 +79,26 @@
 				} catch {
 					// Malformed payload — discard; nothing actionable for the user.
 				}
-			})
+			}),
+			// M11: a host banned someone. If it's us, the session has already been
+			// revoked server-side — drop local auth and send us to /join so the UI
+			// doesn't keep pretending we're signed in.
+			onSseEvent('user-banned', (data) => {
+				try {
+					const payload = JSON.parse(data) as { user_id: string };
+					if (payload.user_id === getUserId()) {
+						clearAuth();
+						toast('Du wurdest vom Event entfernt.', 'error');
+						void goto('/join');
+					}
+				} catch {
+					/* malformed — ignore */
+				}
+			}),
+			// M11: reflect event lock state live so the feed/upload pages can toggle
+			// their "Uploads gesperrt" banner and disable the FAB.
+			onSseEvent('event-closed', () => uploadsLocked.set(true)),
+			onSseEvent('event-opened', () => uploadsLocked.set(false))
 		);
 	});
 
diff --git a/frontend/src/routes/export/+page.svelte b/frontend/src/routes/export/+page.svelte
index f6b6cf7..f97ab74 100644
--- a/frontend/src/routes/export/+page.svelte
+++ b/frontend/src/routes/export/+page.svelte
@@ -23,6 +23,7 @@
 	let status = $state<ExportStatus | null>(null);
 	let showHtmlGuide = $state(false);
 	let loading = $state(true);
+	let loadError = $state(false);
 
 	let unsubscribers: (() => void)[] = [];
 
@@ -53,9 +54,12 @@
 	async function loadStatus() {
 		try {
 			status = await api.get<ExportStatus>('/export/status');
+			loadError = false;
 		} catch {
-			// Background poll triggered by SSE — silent. The visible empty/loading state
-			// will reflect the failure; the next event will retry.
+			// M19: a fetch failure must not masquerade as "not yet released" — only
+			// flag an error when we have nothing to show; a background SSE poll that
+			// fails while we already have a status stays silent.
+			if (!status) loadError = true;
 		} finally {
 			loading = false;
 		}
@@ -174,6 +178,16 @@
 	<div class="mx-auto max-w-lg space-y-4 p-4">
 		{#if loading}
 			<div class="py-16 text-center text-gray-400 dark:text-gray-500">Laden…</div>
+		{:else if loadError}
+			<div class="rounded-xl border border-gray-200 bg-white p-6 text-center dark:border-gray-700 dark:bg-gray-800">
+				<p class="font-medium text-gray-700 dark:text-gray-300">Status konnte nicht geladen werden.</p>
+				<button
+					onclick={() => { loading = true; loadStatus(); }}
+					class="mt-3 rounded-lg bg-blue-600 px-4 py-2 text-sm font-medium text-white transition hover:bg-blue-700"
+				>
+					Erneut versuchen
+				</button>
+			</div>
 		{:else if !status?.released}
 			<div class="rounded-xl border border-gray-200 bg-white p-6 text-center dark:border-gray-700 dark:bg-gray-800">
 				<svg class="mx-auto mb-3 h-12 w-12 text-gray-300 dark:text-gray-600" fill="none" viewBox="0 0 24 24" stroke="currentColor">
diff --git a/frontend/src/routes/feed/+page.svelte b/frontend/src/routes/feed/+page.svelte
index 3da232d..10ca8a5 100644
--- a/frontend/src/routes/feed/+page.svelte
+++ b/frontend/src/routes/feed/+page.svelte
@@ -16,6 +16,7 @@
 	import { toast, toastError } from '$lib/toast-store';
 	import { pullToRefresh } from '$lib/actions/pull-to-refresh';
 	import { vibrate } from '$lib/haptics';
+	import { uploadsLocked } from '$lib/event-state-store';
 	import type { FeedUpload, FeedResponse, HashtagCount, DeltaResponse } from '$lib/types';
 
 	let uploads = $state<FeedUpload[]>([]);
@@ -24,6 +25,7 @@
 	let nextCursor = $state<string | null>(null);
 	let loadingMore = $state(false);
 	let initialLoading = $state(true);
+	let loadError = $state(false);
 	let refreshing = $state(false);
 	let pullProgress = $state(0); // 0–1+ during the drag, 0 when idle
 	let selectedUpload = $state<FeedUpload | null>(null);
@@ -246,13 +248,18 @@
 			const res = await api.get<FeedResponse>(`/feed?${params}`);
 			uploads = res.uploads;
 			nextCursor = res.next_cursor;
+			loadError = false;
 			// Seed the SSE reconnect cursor from the newest server timestamp so the
 			// delta on the next reconnect is based on server time, not the client
 			// clock (M9).
 			if (uploads.length) setLastEventTime(uploads[0].created_at);
 		} catch (e) {
-			// Initial / user-triggered refresh is worth surfacing — background SSE refetches are noisier and silenced below.
-			if (!refresh) toastError(e);
+			// M19: distinguish a load failure from a genuinely empty gallery so the
+			// template can offer a retry instead of showing "nobody posted yet".
+			if (!refresh) {
+				loadError = true;
+				toastError(e);
+			}
 		} finally {
 			initialLoading = false;
 		}
@@ -524,6 +531,16 @@
 		{/if}
 	</div>
 
+	<!-- Uploads-locked banner (M11) -->
+	{#if $uploadsLocked}
+		<div
+			class="mx-auto mb-2 max-w-2xl rounded-lg bg-amber-100 px-4 py-2 text-center text-sm font-medium text-amber-800 dark:bg-amber-900/40 dark:text-amber-200"
+			role="status"
+		>
+			Uploads sind aktuell gesperrt.
+		</div>
+	{/if}
+
 	<!-- Content -->
 	{#if initialLoading && uploads.length === 0}
 		<div class="mx-auto max-w-2xl" data-testid="feed-skeleton">
@@ -539,10 +556,20 @@
 				</div>
 			{/if}
 		</div>
+	{:else if uploads.length === 0 && loadError}
+		<div class="py-20 text-center">
+			<p class="text-lg text-gray-600 dark:text-gray-300">Galerie konnte nicht geladen werden.</p>
+			<button
+				onclick={() => loadFeed()}
+				class="mt-3 rounded-lg bg-blue-600 px-4 py-2 text-sm font-medium text-white transition hover:bg-blue-700"
+			>
+				Erneut versuchen
+			</button>
+		</div>
 	{:else if uploads.length === 0}
 		<div class="py-20 text-center">
-			<p class="text-lg text-gray-400 dark:text-gray-500">Noch keine Fotos.</p>
-			<p class="mt-1 text-sm text-gray-400 dark:text-gray-500">Tippe auf den Plus-Button unten!</p>
+			<p class="text-lg text-gray-500 dark:text-gray-400">Noch keine Fotos.</p>
+			<p class="mt-1 text-sm text-gray-500 dark:text-gray-400">Tippe auf den Plus-Button unten!</p>
 		</div>
 	{:else if viewMode === 'list'}
 		<!-- List view: chronological full-width cards -->