diff --git a/mod/workshop/form/assessment_form.php b/mod/workshop/form/assessment_form.php
index 7ecbcf6738c..56128dcf5b3 100644
--- a/mod/workshop/form/assessment_form.php
+++ b/mod/workshop/form/assessment_form.php
@@ -120,41 +120,4 @@ class workshop_assessment_form extends moodleform {
     public function is_editable() {
         return !$this->_form->isFrozen();
     }
-
-    /**
-     * Validate assessment form data.
-     *
-     * @param array $data
-     * @param array $files
-     * @return array
-     */
-    public function validation($data, $files) {
-
-        $errors = parent::validation($data, $files);
-
-        if (isset($data['feedbackauthorattachment_filemanager']) and isset($this->workshop->overallfeedbackfiletypes)) {
-            $filetypesutil = new \core_form\filetypes_util();
-            $whitelist = $filetypesutil->normalize_file_types($this->workshop->overallfeedbackfiletypes);
-            if ($whitelist) {
-                $draftfiles = file_get_drafarea_files($data['feedbackauthorattachment_filemanager']);
-                if ($draftfiles) {
-                    $wrongfiles = array();
-                    foreach ($draftfiles->list as $file) {
-                        if (!$filetypesutil->is_allowed_file_type($file->filename, $whitelist)) {
-                            $wrongfiles[] = $file->filename;
-                        }
-                    }
-                    if ($wrongfiles) {
-                        $a = array(
-                            'whitelist' => implode(', ', $whitelist),
-                            'wrongfiles' => implode(', ', $wrongfiles),
-                        );
-                        $errors['feedbackauthorattachment_filemanager'] = get_string('err_wrongfileextension', 'mod_workshop', $a);
-                    }
-                }
-            }
-        }
-
-        return $errors;
-    }
 }
diff --git a/mod/workshop/lang/en/deprecated.txt b/mod/workshop/lang/en/deprecated.txt
index 01fea12c442..dc549a1c974 100644
--- a/mod/workshop/lang/en/deprecated.txt
+++ b/mod/workshop/lang/en/deprecated.txt
@@ -1,2 +1,3 @@
 err_unknownfileextension,mod_workshop
+err_wrongfileextension,mod_workshop
 yourassessment,mod_workshop
diff --git a/mod/workshop/lang/en/workshop.php b/mod/workshop/lang/en/workshop.php
index 21df5a6d7c4..6af18ef1ef8 100644
--- a/mod/workshop/lang/en/workshop.php
+++ b/mod/workshop/lang/en/workshop.php
@@ -107,7 +107,6 @@ $string['editingsubmission'] = 'Editing submission';
 $string['editsubmission'] = 'Edit submission';
 $string['err_multiplesubmissions'] = 'While editing this form, another version of the submission has been saved. Multiple submissions per user are not allowed.';
 $string['err_removegrademappings'] = 'Unable to remove the unused grade mappings';
-$string['err_wrongfileextension'] = 'Some files ({$a->wrongfiles}) cannot be uploaded. Only file types {$a->whitelist} are allowed.';
 $string['evaluategradeswait'] = 'Please wait until the assessments are evaluated and the grades are calculated';
 $string['evaluation'] = 'Grading evaluation';
 $string['evaluationmethod'] = 'Grading evaluation method';
@@ -373,3 +372,4 @@ $string['yourassessment'] = 'Your assessment';
 
 // Deprecated since Moodle 3.4.
 $string['err_unknownfileextension'] = 'Unknown file extension: {$a}';
+$string['err_wrongfileextension'] = 'Some files ({$a->wrongfiles}) cannot be uploaded. Only file types {$a->whitelist} are allowed.';
diff --git a/mod/workshop/submission_form.php b/mod/workshop/submission_form.php
index 6b794dcd935..29980feb374 100644
--- a/mod/workshop/submission_form.php
+++ b/mod/workshop/submission_form.php
@@ -94,29 +94,6 @@ class workshop_submission_form extends moodleform {
             $errors['attachment_filemanager'] = get_string('submissionrequiredfile', 'mod_workshop');
         }
 
-        if (isset($data['attachment_filemanager']) and isset($this->_customdata['workshop']->submissionfiletypes)) {
-            $filetypesutil = new \core_form\filetypes_util();
-            $whitelist = $filetypesutil->normalize_file_types($this->_customdata['workshop']->submissionfiletypes);
-            if ($whitelist) {
-                $draftfiles = file_get_drafarea_files($data['attachment_filemanager']);
-                if ($draftfiles) {
-                    $wrongfiles = array();
-                    foreach ($draftfiles->list as $file) {
-                        if (!$filetypesutil->is_allowed_file_type($file->filename, $whitelist)) {
-                            $wrongfiles[] = $file->filename;
-                        }
-                    }
-                    if ($wrongfiles) {
-                        $a = array(
-                            'whitelist' => implode(', ', $whitelist),
-                            'wrongfiles' => implode(', ', $wrongfiles),
-                        );
-                        $errors['attachment_filemanager'] = get_string('err_wrongfileextension', 'mod_workshop', $a);
-                    }
-                }
-            }
-        }
-
         return $errors;
     }
 }