Hello Bettina!
Thank you for your response.
I have uninstalled all the plugins except tagdiv plugins and again I am facing the same problem.
I uninstalled and reinstalled also the tagdiv plugins and again the same problem.
About theme requirements, I do not see any problem there.
Thank you for the links send to me, I read them but was not able to solve the problem.
Please find attached the screenshot of my System status