How to solve this problem if there is An error occurred while loading the PDF

Hi @Jurnal_Nizham_IAIN_M

Could you double check if your files exists and are correctly migrated in your files_dir?
Also, have you already searched after the similar issues in this forum, read them and tried the solutions from there? S. for example: Pdf viewer not see pdf file - #3 by ctgraham or Can't download or view pdf files - #25 by desilvarami


also check the permissions of file_dir