File upload error. Could not move uploaded file.
In Drupal, in example, version 7, you need to check the following if you encounter the error: "File upload error. Could not move uploaded file."
Check that a temporary directory is present and correctly configured in File System
By default you need to set, ensure that existing, a corresponding folder for Drupal's requirement as required in /admin/config/media/file-system. In below example you should have a folder named temporary in /yourwebsiterootfolder/temporary. Sometimes, pre-configured settings has folder named as "tmp" or may also be located someplace else.
Ensure proper permissions are correctly set. Normally, it is safe to leave all permissions by default Drupal installation as changing permissions to directories are dangerous. Check Drupal documentation.
Check with your webhosting provider that there are no limitations or restrictions in uploading files. Certain configurations may be needed in your php.ini or .htaccess files in which case your webhosting provider can best assist.
Disk storage or File quota
Check with your CPanel or your hosting that you are not exceeding disk or storage quota. Same error will appear if you are.