cpanel is not working after CWP migration

I finished the migration normally for all my accounts.
I rebuild the vhosts for all my domains.
The problem is that after a total renovation of all the SSL certificates even though the webmail, mail, and ftp works normally the cpanel shows a  HTTP ERROR 500.
I tried to disable firewall, modescurity and remove the SSL for some of the accounts to test but again the problem is there.
Even a reboot did not fix the issue.
If i ping to cpanel.domain i get normally response but the panel won't open.
I tried to repair the user permission but again no luck.
Does anyone has any idea why that happened? I never had such and issue before.

The issue is the same as this one --> https://forum.centos-webpanel.com/index.php?topic=8950.0

I tested the script provided by rcschaff here --> http://forum.centos-webpanel.com/index.php?topic=8980.0

After some hours searching and testing and reviewing the logs the solution was much much easier and provide it here to save some people from headaches 

If after an upgrade or migration you are unable to use user panel and getting the HTTP 500 error then follow the next steps to fix the issue.
1. Login to your panel
2. Select User Accounts --> Features,Themes,Languages
3. Select everything to the tab "Themes"
4. Hit the button "Save Theme Default"
5. Change if again to your theme or just leave it as it is
6. Enjoy the magic and do not forget to leave a thumb up as no script was used finally!

I was suffering to find out the problem and worse than that I did what you advised and it worked thank you kkk