Unable to upgrade plugin

I am not able to upgrade plugin to newer version. The error message says it might be permission issue. I checked for permission but it was okay. I am Using OJS version

Hi @dwangdi

Can you perform upgrade through command line? This probably will give more information about what’s going on.

Note: before any update it’s better to make a backup of OJS’s database, a directory in which uploaded files are stored and OJS webroot files (the latter can help in case if custom changes were done in the code, restore files uploaded in the public dir if they are mistakenly deleted, or restore OJS config settings from a correspondent file).

Let me know if you haven’t got access to the command line.