diff --git a/ui/index.html b/ui/index.html
index 106ad6a..f545b13 100644
--- a/ui/index.html
+++ b/ui/index.html
@@ -23,6 +23,11 @@
       it's ID is <code id="jobid"></code>
     </div>
 
+    <div id="error-alert" class="alert alert-danger" style="display: none;">
+      <strong>An error occurs:</strong>
+      <span id="errortxt"></span>
+    </div>
+
     <div id="volumes-card" class="mb-3 card" style="display: none;">
       <h5 class="card-header">
         Volumes
diff --git a/ui/js/minifass.js b/ui/js/minifass.js
index 5fd549b..d5c93a5 100644
--- a/ui/js/minifass.js
+++ b/ui/js/minifass.js
@@ -13,10 +13,15 @@ let current_job = null;
 function runctnr() {
   document.getElementById("btnlaunch").disabled = true;
   document.getElementById("btnlaunchspinner").style.display = "inline-block";
+  document.getElementById("error-alert").style.display = "none";
 
   fetch('/api/run')
     .then(function(response) {
-      return response.json();
+      if (response.status >= 200 && response.status <= 299) {
+        return response.json();
+      } else {
+        throw response;
+      }
     })
     .then(function(data) {
       current_job = data.jobid;
@@ -26,6 +31,15 @@ function runctnr() {
 
       fetchLogs();
     })
+    .catch(function(error) {
+      error.json().then(json => {
+        document.getElementById("errortxt").textContent = json.error;
+        document.getElementById("error-alert").style.display = "block";
+      })
+
+      document.getElementById("btnlaunch").disabled = false;
+      document.getElementById("btnlaunchspinner").style.display = "none";
+    })
   return false;
 }