PLUGINS page don't load up. Error after Upgrade from OJS 3.1.2 to

I have upgraded recently from OJS 3.1.2 to
And now I can’t see the list of plugins because PLUGINS tabs always spinning and doesn’t load up.

[26-Nov-2019 09:58:32 UTC] PHP Fatal error: Uncaught Error: Call to a member function getCurrent() on null in /home/naeemijr/public_html/
Stack trace:
#0 /home/naeemijr/public_html/ VersionDAO->insertVersion(NULL, true)
#1 /home/naeemijr/public_html/ PluginGridHandler->loadCategoryData(Object(Request), ‘generic’, Array)
#2 /home/naeemijr/public_html/ SettingsPluginGridHandler->loadCategoryData(Object(Request), ‘generic’, Array)
#3 /home/naeemijr/public_html/ CategoryGridHandler->getGridCategoryDataElements(Object(Request), ‘generic’)
#4 /home/naeemijr/public_html/ CategoryGridHandler->_renderCategoryInternally(Objec in /home/naeemijr/public_html/ on line 135

I have tried upgrading plugins, but didn’t worked. Please help me out.
Naveen Malik

Hi @navmalik,

Was the upgrade process successful? Can you double check if you current OJS code is identical to the original OJS code from the release package?

Yes, the upgrade was successful. But I don’t know how to check the code ?
Can you guide me how to check the code with original package?

Hi @navmalik,

You can compare the code with Diff Tools. There are many of them available on the Internet.
Before that, can you describe how you performed an upgrade? Are all of the plugins that you are using compatible with the OJS release to which you have upgraded?

Thank you for your response.
But I have upgraded again and now it works fine.