I ran into the problem with the
"Function 'oeThemeSwitcherGetUserAgent' does not exist or is not accessible!"
and I found many in this forum who had the same problem, but I did not find how they solve it.
therefore, I figured it out myself and I want to post it for the people to come.
Problem: In 4.8.x if you disable all modules with the SQL below, you will not be able to login into your shop anymore. (WHITE SCREEN). This is know bug (https://bugs.oxid-esales.com/view.php?id=5976)
In the file EXCEPTION_LOG.txt there will be the error:
Function ‘oeThemeSwitcherGetUserAgent’ does not exist or is not accessible!
(NOTE: You can disable all modules with the SQL:
delete from oxconfig where oxvarname in ( “aDisabledModules”, “aLegacyModules”, “aModuleFiles”, “aModulePaths”, “aModules”, “aModuleTemplates” );
Sometimes it is necessary to disable all modules, because you messed to with the metadata.php during module-Development or you have problems with newly installed modules)
Just delete [I]all[/I] content of the tmp folder. [/B]
My problem was, that I deleted everything in the tmp/smarty folder, which is enough when you what to delete your webpage cache.
And my modules to cleam the TEMP folder will also only delete everything in the tmp/smarty folder.
After that, I did not have to clean anything else in the tables oxconfig or oxconfigdisplay as suggested in other posts.
[B]Note:[/B] If you read this, after you have tried different other solution, just start over again.
1.) Disable all the modules with the above sql
2.) delete everything in the tmp folder
3.) login into the admin console.
[B]Thanx:[/B] to all the people in the other posts, who always said, that deleting the temp folder will help. Since in every posts, the people still had the problem, I thought, that this will not help. But it was the answer all the time! Thanx.