diff --git a/backend/__tests__/routes/adminCategoriesNameLength.test.js b/backend/__tests__/routes/adminCategoriesNameLength.test.js
new file mode 100644
index 00000000..6d0a7915
--- /dev/null
+++ b/backend/__tests__/routes/adminCategoriesNameLength.test.js
@@ -0,0 +1,76 @@
+/**
+ * photo_categories.name is varchar(100). Without a length check the insert
+ * hit Postgres' "value too long" and the route's catch turned it into a raw
+ * 500 with no message the form could surface — a >100-char name must come
+ * back as a normal 400 validation error instead.
+ */
+const path = require('path');
+const fs = require('fs');
+const os = require('os');
+
+process.env.NODE_ENV = 'test';
+process.env.TEST_DATABASE_PATH = path.join(
+  fs.mkdtempSync(path.join(os.tmpdir(), 'picpeak-catlen-')), 'db.sqlite',
+);
+process.env.JWT_SECRET = process.env.JWT_SECRET || 'catlen-test-secret';
+process.env.STORAGE_PATH = fs.mkdtempSync(path.join(os.tmpdir(), 'picpeak-catlen-storage-'));
+
+const request = require('supertest');
+const express = require('express');
+const cookieParser = require('cookie-parser');
+const { bootCrmDb, seedMinimal, assignAdminRole, mintAdminToken } = require('../integration/helpers/crmDb');
+
+const TOO_LONG = 'z'.repeat(101);
+
+describe('category name length validation', () => {
+  let db; let cleanup; let app; let superTok;
+
+  const auth = (req) => req.set('Authorization', `Bearer ${superTok}`);
+
+  beforeAll(async () => {
+    ({ db, cleanup } = await bootCrmDb());
+    const { adminId: superId } = await seedMinimal(db);
+    await assignAdminRole(db, superId, 'super_admin');
+    superTok = mintAdminToken(superId);
+
+    app = express();
+    app.use(express.json());
+    app.use(cookieParser());
+    app.use('/api/admin/categories', require('../../src/routes/adminCategories'));
+  }, 120000);
+
+  afterAll(async () => { if (cleanup) await cleanup(); });
+
+  it('rejects a >100-char name on create with a 400, not a 500', async () => {
+    const res = await auth(request(app).post('/api/admin/categories'))
+      .send({ name: TOO_LONG, is_global: true });
+
+    expect(res.status).toBe(400);
+    expect(res.body.errors.some((e) => e.path === 'name')).toBe(true);
+    const rows = await db('photo_categories').where('name', TOO_LONG);
+    expect(rows).toHaveLength(0);
+  });
+
+  it('rejects a >100-char name on update with a 400, not a 500', async () => {
+    const created = await auth(request(app).post('/api/admin/categories'))
+      .send({ name: 'zzcatlen-ok', is_global: true });
+    expect(created.status).toBe(200);
+
+    const res = await auth(request(app).put(`/api/admin/categories/${created.body.id}`))
+      .send({ name: TOO_LONG });
+
+    expect(res.status).toBe(400);
+    expect(res.body.errors.some((e) => e.path === 'name')).toBe(true);
+    const row = await db('photo_categories').where('id', created.body.id).first();
+    expect(row.name).toBe('zzcatlen-ok');
+  });
+
+  it('still accepts a name at exactly the 100-char limit', async () => {
+    const name = 'y'.repeat(100);
+    const res = await auth(request(app).post('/api/admin/categories'))
+      .send({ name, is_global: true });
+
+    expect(res.status).toBe(200);
+    expect(res.body.name).toBe(name);
+  });
+});
diff --git a/backend/src/routes/adminCategories.js b/backend/src/routes/adminCategories.js
index d5ae2404..e7bddada 100644
--- a/backend/src/routes/adminCategories.js
+++ b/backend/src/routes/adminCategories.js
@@ -40,7 +40,11 @@ router.get('/event/:eventId', adminAuth, requirePermission('settings.view'), req
 
 // Create a new category
 router.post('/', adminAuth, requirePermission('settings.edit'), [
-  body('name').notEmpty().withMessage('Category name is required'),
+  // photo_categories.name is varchar(100) — without the length check Postgres
+  // raises "value too long" and the catch below turns it into a raw 500 with
+  // no usable message for the form.
+  body('name').notEmpty().withMessage('Category name is required')
+    .isLength({ max: 100 }).withMessage('Category name must be at most 100 characters'),
   body('slug').optional(),
   body('is_global').optional().isBoolean(),
   body('event_id').optional().isInt(),
@@ -127,7 +131,8 @@ router.post('/', adminAuth, requirePermission('settings.edit'), [
 
 // Update a category
 router.put('/:id', adminAuth, requirePermission('settings.edit'), [
-  body('name').notEmpty().withMessage('Category name is required'),
+  body('name').notEmpty().withMessage('Category name is required')
+    .isLength({ max: 100 }).withMessage('Category name must be at most 100 characters'),
   body('hero_photo_id').optional({ nullable: true }).custom((value) => {
     if (value === null || value === undefined) return true;
     return Number.isInteger(Number(value));
diff --git a/frontend/src/components/admin/CategoryManager.tsx b/frontend/src/components/admin/CategoryManager.tsx
index 786d28ad..712b0829 100644
--- a/frontend/src/components/admin/CategoryManager.tsx
+++ b/frontend/src/components/admin/CategoryManager.tsx
@@ -138,6 +138,7 @@ export const CategoryManager: React.FC = () => {
             onChange={(e) => setNewCategoryName(e.target.value)}
             onKeyPress={(e) => e.key === 'Enter' && handleCreate()}
             placeholder={t('categories.categoryName')}
+            maxLength={100}
             className="flex-1 px-3 py-2 border border-neutral-300 dark:border-neutral-600 rounded-md bg-white dark:bg-neutral-800 text-neutral-900 dark:text-neutral-100 focus:ring-2 focus:ring-primary-500"
             autoFocus
           />
@@ -188,6 +189,7 @@ export const CategoryManager: React.FC = () => {
                       if (e.key === 'Enter') handleUpdate(category.id);
                       if (e.key === 'Escape') cancelEdit();
                     }}
+                    maxLength={100}
                     className="flex-1 px-3 py-1 border border-neutral-300 dark:border-neutral-600 rounded-md bg-white dark:bg-neutral-800 text-neutral-900 dark:text-neutral-100 focus:ring-2 focus:ring-primary-500"
                     autoFocus
                   />
diff --git a/frontend/src/components/admin/EventCategoryManager.tsx b/frontend/src/components/admin/EventCategoryManager.tsx
index cfcea573..a49127f1 100644
--- a/frontend/src/components/admin/EventCategoryManager.tsx
+++ b/frontend/src/components/admin/EventCategoryManager.tsx
@@ -206,6 +206,7 @@ export const EventCategoryManager: React.FC<EventCategoryManagerProps> = ({ even
             onChange={(e) => setNewCategoryName(e.target.value)}
             onKeyPress={(e) => e.key === 'Enter' && handleCreate()}
             placeholder={t('categories.categoryName')}
+            maxLength={100}
             className="flex-1 px-3 py-1.5 text-sm border border-neutral-300 dark:border-neutral-600 rounded-md bg-white dark:bg-neutral-800 text-neutral-900 dark:text-neutral-100 focus:ring-2 focus:ring-primary-500"
             autoFocus
           />