diff --git a/app.py b/app.py
index 0da4647..87d395b 100644
--- a/app.py
+++ b/app.py
@@ -613,6 +613,20 @@ def _shares_with_usage():
     return result
 
 
+def _quota_supported():
+    """Return (supported: bool, reason: str). Checks filesystem type under /srv."""
+    r = subprocess.run(['df', '-T', '/srv'], capture_output=True, text=True)
+    for line in r.stdout.splitlines()[1:]:
+        parts = line.split()
+        if len(parts) >= 2:
+            fstype = parts[1].lower()
+            if fstype == 'zfs':
+                return False, 'ZFS storage detected — Linux disk quotas are not available inside a ZFS-backed container. Manage per-dataset quotas from the Proxmox host with: zfs set quota=10G <dataset>'
+            if fstype in ('tmpfs', 'overlay', 'aufs'):
+                return False, f'{fstype} filesystem does not support disk quotas'
+    return True, ''
+
+
 def _quota_usage():
     try:
         r = subprocess.run(['repquota', '-u', '/srv'], capture_output=True, text=True, timeout=10)
@@ -649,11 +663,14 @@ def _quota_usage():
 @app.route('/api/dashboard', methods=['GET'])
 @require_auth
 def get_dashboard():
+    quota_ok, quota_reason = _quota_supported()
     return jsonify({
         'status': _daemon_status(),
         'disk': _disk_usage(),
         'shares': _shares_with_usage(),
-        'quotas': _quota_usage(),
+        'quotas': _quota_usage() if quota_ok else [],
+        'quota_supported': quota_ok,
+        'quota_reason': quota_reason,
     })
 
 
diff --git a/static/js/dashboard.js b/static/js/dashboard.js
index 0f6d42b..02628aa 100644
--- a/static/js/dashboard.js
+++ b/static/js/dashboard.js
@@ -36,8 +36,14 @@ async function loadDashboard() {
             </tr>`).join('');
     }
 
+    // Persist quota support flag for shares.js to read
+    window._quotaSupported = d.quota_supported !== false;
+    window._quotaReason = d.quota_reason || '';
+
     const qb = document.getElementById('dashQuotasBody');
-    if (!d.quotas?.length) {
+    if (!d.quota_supported) {
+        qb.innerHTML = `<tr><td colspan="4" style="color:var(--muted); font-size:.87rem">${esc(d.quota_reason)}</td></tr>`;
+    } else if (!d.quotas?.length) {
         qb.innerHTML = `<tr><td colspan="4" style="color:var(--muted)">No quotas set.</td></tr>`;
     } else {
         qb.innerHTML = d.quotas.map(q => {
diff --git a/static/js/shares.js b/static/js/shares.js
index 6e6603a..fba41fa 100644
--- a/static/js/shares.js
+++ b/static/js/shares.js
@@ -23,8 +23,8 @@ async function loadShares() {
                 <td>
                     <button class="btn btn-sm me-1" style="border:1px solid var(--border); color:var(--muted)"
                         onclick="openEditModal('smb',${shareJson})">Edit</button>
-                    <button class="btn btn-sm me-1" style="border:1px solid var(--border); color:var(--muted)"
-                        onclick="openQuotaModal('smb',${nameJson},${pathJson},${usersJson})">Quota</button>
+                    ${window._quotaSupported !== false ? `<button class="btn btn-sm me-1" style="border:1px solid var(--border); color:var(--muted)"
+                        onclick="openQuotaModal('smb',${nameJson},${pathJson},${usersJson})">Quota</button>` : ''}
                     <button class="btn btn-sm me-1" style="border:1px solid var(--border); color:var(--muted)"
                         onclick="toggleShare('smb',${nameJson},${!enabled})">${enabled ? 'Disable' : 'Enable'}</button>
                     <button class="btn btn-sm btn-danger"
@@ -50,8 +50,8 @@ async function loadShares() {
                 <td>
                     <button class="btn btn-sm me-1" style="border:1px solid var(--border); color:var(--muted)"
                         onclick="openEditModal('nfs',${shareJson})">Edit</button>
-                    <button class="btn btn-sm me-1" style="border:1px solid var(--border); color:var(--muted)"
-                        onclick="openQuotaModal('nfs',null,${pathJson},null)">Quota</button>
+                    ${window._quotaSupported !== false ? `<button class="btn btn-sm me-1" style="border:1px solid var(--border); color:var(--muted)"
+                        onclick="openQuotaModal('nfs',null,${pathJson},null)">Quota</button>` : ''}
                     <button class="btn btn-sm me-1" style="border:1px solid var(--border); color:var(--muted)"
                         onclick="toggleShare('nfs',${pathJson},${!enabled})">${enabled ? 'Disable' : 'Enable'}</button>
                     <button class="btn btn-sm btn-danger"