php - Ckeditor Invalid file

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Hi Iam using ckeditor for my site , here on clicking browse server ,it list out the folders but on uploading certain file , it rasies an error 'invalid file' , I checked the ckeditor config(config.php) file for extension and I uploaded the allowed extension ,but the same issue occurs ,also I checked my php.ini whether file_upload was turned 'off' but it is 'on' , Can anybody help me with this issue please?