diff --git a/app/src/main/java/com/nutomic/syncthingandroid/activities/WebGuiActivity.java b/app/src/main/java/com/nutomic/syncthingandroid/activities/WebGuiActivity.java
index 1b5f2b1e..04688ce0 100644
--- a/app/src/main/java/com/nutomic/syncthingandroid/activities/WebGuiActivity.java
+++ b/app/src/main/java/com/nutomic/syncthingandroid/activities/WebGuiActivity.java
@@ -19,6 +19,7 @@ import android.webkit.HttpAuthHandler;
 import android.webkit.SslErrorHandler;
 import android.webkit.WebView;
 import android.webkit.WebViewClient;
+import android.widget.Toast;
 
 import com.nutomic.syncthingandroid.R;
 import com.nutomic.syncthingandroid.service.Constants;
@@ -206,13 +207,18 @@ public class WebGuiActivity extends StateDialogActivity
     }
 
     /**
-     * Reads the SyncthingService.HTTPS_CERT_FILE Ca Cert key  and loads it in memory
+     * Reads the SyncthingService.HTTPS_CERT_FILE Ca Cert key and loads it in memory
      */
     private void loadCaCert() {
         InputStream inStream = null;
+        File httpsCertFile = Constants.getHttpsCertFile(this);
+        if (!httpsCertFile.exists()) {
+            Toast.makeText(WebGuiActivity.this, R.string.config_file_missing, Toast.LENGTH_LONG).show();
+            finish();
+            return;
+        }
         try {
-            File httpsCertPath = Constants.getHttpsCertFile(this);
-            inStream = new FileInputStream(httpsCertPath);
+            inStream = new FileInputStream(httpsCertFile);
             CertificateFactory cf = CertificateFactory.getInstance("X.509");
             mCaCert = (X509Certificate)
                     cf.generateCertificate(inStream);
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 6c0e7ff6..d30df4b6 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -583,6 +583,9 @@ Please report any problems you encounter via Github.</string>
     <!-- Toast shown if syncthing failed to create a config -->
     <string name="config_create_failed">Failed to create config file</string>
 
+    <!-- Toast shown if a config file crucial to operation is missing -->
+    <string name="config_file_missing">A config file crucial to operation is missing</string>
+
     <!-- Label of the default folder created of first start (camera folder). -->
     <string name="default_folder_label">Camera</string>