diff --git a/books/views.py b/books/views.py
index 8ed0203..701798b 100644
--- a/books/views.py
+++ b/books/views.py
@@ -447,7 +447,7 @@ def upload_book(request):
         return JsonResponse({'error': 'invalid base64 in data_ct'}, status=400)
 
     if raw_size > max_bytes:
-        return JsonResponse({'error': 'file too large (max 50 MB)'}, status=400)
+        return JsonResponse({'error': f'file too large (max {settings.EBOOK_MAX_BYTES // (1024 * 1024)} MB)'}, status=400)
 
     book = EBook.objects.create(
         user=request.user,
diff --git a/diora/settings.py b/diora/settings.py
index 5bd586c..88ce3af 100644
--- a/diora/settings.py
+++ b/diora/settings.py
@@ -34,10 +34,10 @@ INSTALLED_APPS = [
     'feeds',
 ]
 
-EBOOK_MAX_BYTES = 50 * 1024 * 1024  # 50 MB
+EBOOK_MAX_BYTES = 100 * 1024 * 1024  # 100 MB (big scanned PDFs, complete editions)
 
-# Encrypted uploads are base64-encoded (~33% overhead) so allow ~75 MB body
-DATA_UPLOAD_MAX_MEMORY_SIZE = 75 * 1024 * 1024
+# Encrypted uploads are base64-encoded (~33% overhead) so allow ~140 MB body
+DATA_UPLOAD_MAX_MEMORY_SIZE = 140 * 1024 * 1024
 
 MIDDLEWARE = [
     'django.middleware.security.SecurityMiddleware',
diff --git a/static/js/app/01-core.js b/static/js/app/01-core.js
index 4dbbfef..6c15919 100644
--- a/static/js/app/01-core.js
+++ b/static/js/app/01-core.js
@@ -137,7 +137,7 @@ const _GERMAN_ERRORS = {
   'file must be .m3u or .m3u8': 'Die Datei muss eine .m3u- oder .m3u8-Datei sein.',
   'no file uploaded': 'Keine Datei hochgeladen.',
   'only jpeg, png, or webp allowed': 'Nur JPEG, PNG oder WebP erlaubt.',
-  'file too large (max 50 MB)': 'Datei zu groß (höchstens 50 MB).',
+  'file too large (max 100 MB)': 'Datei zu groß (höchstens 100 MB).',
   'file too large (max 5 MB)': 'Datei zu groß (höchstens 5 MB).',
   'authentication required': 'Bitte anmelden.',
   'not found': 'Nicht gefunden.',
diff --git a/static/js/app/52-book-list.js b/static/js/app/52-book-list.js
index 38ba91b..7479f32 100644
--- a/static/js/app/52-book-list.js
+++ b/static/js/app/52-book-list.js
@@ -589,24 +589,48 @@ function bookFileSelected(input) {
 // and author) is left out. statusEl shows how far it is and, at the end, what came of it.
 async function _importMany(items, statusEl) {
   statusEl = statusEl || $('book-upload-status');
-  const done = {ok: 0, dup: 0, failed: []};
+  const done = {ok: 0, dup: 0, failed: [], big: []};
+  const retry = [];
+  const wait = ms => new Promise(r => setTimeout(r, ms));
   for (let i = 0; i < items.length; i++) {
     const it = items[i];
-    if (statusEl) statusEl.textContent = `Buch ${i + 1} von ${items.length}: „${it.name}“ …`;
-    if (it.size && it.size > DIORA_CONFIG.ebookMaxBytes) { done.failed.push(it.name + ' (zu groß)'); continue; }
-    try {
-      const r = await _importEbookBuffer(await it.buf(), it.name, null, {reload: false, skipKnown: true});
-      if (r === 'dup') done.dup++;
-      else if (r) done.ok++;
-      else done.failed.push(it.name);
-    } catch (e) {
-      done.failed.push(it.name);
+    if (it.size && it.size > DIORA_CONFIG.ebookMaxBytes) { done.big.push(it.name); continue; }
+    // A failure is tried again, a little later each time: the server may be restarting
+    // (an update) or the connection gone for a moment — not a reason to lose the rest.
+    let r = false;
+    for (let attempt = 0; attempt < 4 && r === false; attempt++) {
+      if (attempt) {
+        if (statusEl) statusEl.textContent = `Buch ${i + 1} von ${items.length}: „${it.name}“ – neuer Versuch …`;
+        await wait([0, 3000, 8000, 20000][attempt]);
+      }
+      if (statusEl && !attempt) statusEl.textContent = `Buch ${i + 1} von ${items.length}: „${it.name}“ …`;
+      try {
+        r = await _importEbookBuffer(await it.buf(), it.name, null, {reload: false, skipKnown: true});
+      } catch (e) {
+        r = false;
+      }
     }
+    if (r === 'dup') done.dup++;
+    else if (r) done.ok++;
+    else { done.failed.push(it.name); retry.push(it); }
   }
+  const mb = Math.round(DIORA_CONFIG.ebookMaxBytes / 1024 / 1024);
   const parts = [`✓ ${done.ok} ${done.ok === 1 ? 'Buch' : 'Bücher'} hinzugefügt`];
   if (done.dup) parts.push(`${done.dup} schon da`);
+  if (done.big.length) parts.push(`zu groß (über ${mb} MB): ${done.big.join(', ')}`);
   if (done.failed.length) parts.push(`nicht geklappt: ${done.failed.join(', ')}`);
-  if (statusEl) statusEl.textContent = parts.join(' · ');
+  if (statusEl) {
+    statusEl.textContent = parts.join(' · ');
+    if (retry.length) {
+      const again = document.createElement('button');
+      again.type = 'button';
+      again.className = 'btn btn-sm';
+      again.style.marginLeft = '8px';
+      again.textContent = `${retry.length} erneut versuchen`;
+      again.onclick = () => _importMany(retry, statusEl);
+      statusEl.appendChild(again);
+    }
+  }
   if (done.ok) loadBookList();
   return done;
 }
diff --git a/static/js/sw.js b/static/js/sw.js
index 80ad434..a69672f 100644
--- a/static/js/sw.js
+++ b/static/js/sw.js
@@ -2,7 +2,7 @@
  * diora service worker — caches the app shell for offline use.
  */
 
-const CACHE = 'diora-v122';
+const CACHE = 'diora-v123';
 const SHELL = [
   '/static/css/app.css',
   '/static/js/app/01-core.js',