The WordPress Admin 500 error bug could make you very sad after an upgrade;
If you have discovered this error or you are havi ng a white screen after the upgrade.
open: public_html/wp-admin in your Cpanel, try to navigate to the error log. Click on it and click "View"
Step two : follow the error indications to locate the possible files that are behind the issue, normally if it is a plugin that you just installed, simply deleting it will solve the problem.
If it was not a plugin but a core update that caused the problem, simply open: public_html/wp-admin, then click "create file" at the top left then name the file php.ini
then copy this code
memory=256MB paste it the file that you just created. then click on save. Step three: Go to your browser, then try to open your wp-admin if it does not open ; then open your Cpanel or login to your Cpanel, then go to the "software" section
then click on php selector
then click on "switch to php options"
then click on the number close to "memory_limit" and select 128 or 256MB as you may wish, then click on save. then wait 7 to 8 mins, you will then try again to access your wp-admin, normally you should be able to access it confortably. If you do not have access to your Cpanel to be able to resulve the issue accordingly as described in this tutorial, simply contact your webhost. Please leave a comment after applying this tutorial, so that we ensure that you are happy. if you have a particular difficulty simply contact us or leave a feedback