diff --git a/stack/cas/connector.server.class.php b/stack/cas/connector.server.class.php
index b8c33a1dcf9..7ca3e69b52e 100644
--- a/stack/cas/connector.server.class.php
+++ b/stack/cas/connector.server.class.php
@@ -69,8 +69,8 @@ protected function call_maxima($command) {
         // Did we get files?
         if (strpos(curl_getinfo($request, CURLINFO_CONTENT_TYPE), "text/plain") === false) {
             // We have to save the zip file on local disk before opening.
-            $ziptemp = tempnam($CFG->dataroot . '/stack/tmp/', 'zip');
-            file_put_contents($ziptemp, $ret);
+            $ziptemp = @tempnam($CFG->dataroot . '/stack/tmp/', 'zip');
+            @file_put_contents($ziptemp, $ret);
 
             // Loop over the contents of the zip.
             $zip = new ZipArchive();
@@ -85,7 +85,7 @@ protected function call_maxima($command) {
                 } else {
                     // Otherwise this is a plot.
                     $filename = $CFG->dataroot . "/stack/plots/" . $filenameinzip;
-                    file_put_contents($filename, $zip->getFromIndex($i));
+                    @file_put_contents($filename, $zip->getFromIndex($i));
                 }
             }
 
diff --git a/stack/cas/connector.server_proxy.class.php b/stack/cas/connector.server_proxy.class.php
index 8bafacde45d..7aa27de1d92 100644
--- a/stack/cas/connector.server_proxy.class.php
+++ b/stack/cas/connector.server_proxy.class.php
@@ -94,8 +94,8 @@ protected function call_maxima($command) {
         // Did we get files?
         if (strpos(curl_getinfo($request, CURLINFO_CONTENT_TYPE), "text/plain") === false) {
             // We have to save the zip file on local disk before opening.
-            $ziptemp = tempnam($CFG->dataroot . '/stack/tmp/', 'zip');
-            file_put_contents($ziptemp, $ret);
+            $ziptemp = @tempnam($CFG->dataroot . '/stack/tmp/', 'zip');
+            @file_put_contents($ziptemp, $ret);
 
             // Loop over the contents of the zip.
             $zip = new ZipArchive();
@@ -110,7 +110,7 @@ protected function call_maxima($command) {
                 } else {
                     // Otherwise this is a plot.
                     $filename = $CFG->dataroot . "/stack/plots/" . $filenameinzip;
-                    file_put_contents($filename, $zip->getFromIndex($i));
+                    @file_put_contents($filename, $zip->getFromIndex($i));
                 }
             }
 
diff --git a/stack/cas/installhelper.class.php b/stack/cas/installhelper.class.php
index 94b2196a7f0..71c54330dbe 100644
--- a/stack/cas/installhelper.class.php
+++ b/stack/cas/installhelper.class.php
@@ -219,7 +219,7 @@ public static function create_maximalocal() {
         make_upload_directory('stack/plots');
         make_upload_directory('stack/tmp');
 
-        if (!file_put_contents(self::maximalocal_location(), self::generate_maximalocal_contents())) {
+        if (!@file_put_contents(self::maximalocal_location(), self::generate_maximalocal_contents())) {
             throw new stack_exception('Failed to write Maxima configuration file.');
         }
     }