Regarding the error: An unexpected error has occurred. Please reload the page and try again

Describe the issue or problem
An unexpected error has occurred. Please reload the page and try again.

Steps I took leading up to the issue
For example:

  1. When we login, this error is shown in pop up.
  2. When we click on view, article is not opening only loading the page
  3. We can not do anything in this error.

What application are you using?
OJS 3.3.0.8.

Kindly guide what is the issue in this case.

Please check error log file . what errors are registering in it ?

Regards
PKP Team