Suddenly, when opening project center in SharePoint 2013 a message appeared
And nothing found in the log.
Unexpected error or unknown error in project center is an ambiguous error that should be traced based on each scenario by checking the Event Viewer and trace log. so please check the below investigation steps:
First, I suggest editing all views in project center to be filtered with the project published date to be less than the date before the problem occurred by following:
Most of the cases refer to an error occurred in project information that you recently published. so try to trace the latest projects you have published and open it with Microsoft project and check the resources and basic information and try to publish it again.
Second, Check the Event Viewer to get the root cause of the issue.I wrote an article before related to this issue but as I told you it differ based on each scenario, so please check it at AN UNKNOWN ERROR HAS OCCURRED INSIDE PROJECT CENTER IN PROJECT SERVER may be it the same case.