Try to disable friendly URLs and/or refresh their setting.

Thank you. listing links works fine now.

But the upgrade button still not working. Here is the debug log

"[04-Apr-2023 16:02:10 Asia/Kolkata] PHP Fatal error:  Allowed memory size of 134217728 bytes exhausted (tried to allocate 20971520 bytes) in /home/*****/public_html/oc-includes/osclass/utils.php on line 1659"

You may try to increase allowed memory, but this one cannot be well debugged.

okay. but i have another domain running using the same configuration. It has no problem.

where should i increase memory limits? php.ini?

Yes or php settings on hosting.