Virtuemart - Problems in backend with "shop" and "images"

[RensvN]

One of my webshops is running on Joomla 3.9.1 in combination with Virtuemart 3.4.2
I just find out that some pieces in the backend of my webshop do not work properly, I don't know how to solve this to be honest.

Everything seems to work properly exept one are of the backend.
I'm facing some problems while I click on "Virtuemart" and than "Shop" or "images"
I can't edit some crucial details of my webshop (see attached images)

Is it an problem with my database or is it something else?

[Studio 42]

This is a typical PHP error, you need to get last virtuemart 3.4.3 Beta release when you use Joomla 3.9
Get last package from here http://dev.virtuemart.net/projects/virtuemart/files

[RensvN]

I just updated to VM 3.4.3 unfortunately without any result.

[Studio 42]

Enable PHP erro display in your Joomla config and check if you see any error message.

[GJC Web Design]

and enable Joomla debug and you can see the file error trace as well

[RensvN]

I did put "debugging system" on "yes" and "error reporting" on "development" but there is no error message showing up.

[GJC Web Design]

logged elsewhere on your server?

[RensvN]

How can I see that?

[Studio 42]

How can I see that?

Most time in your Joomla root folder error.log or in a log subfolder or sometime directly in server panel

[RensvN]

I just checked and I saw one map named "logs".
It contains some .tar.gz files, is that what I need?

How can I open these files and wich one do I need?

[jenkinhill]

Could be access or ftp log files. The hint will be in the use of the word "error" in the filename.

Assuming this is a recent Joomla installation, site errors are logged in administrator/logs - look for error.php or com_virtuemart.log.php

[RensvN]

I found some error file but the only message within the file is about an incorrect combination of username and password.

Any other ideas?

[jenkinhill]

I presume you have tried to reinstall the VM components? Sometimes issues like this are related to installation issues.

[RensvN]

Yes I reinstalled all VM files.

Any idea how to solve this problem?

[GJC Web Design]

JavaScript errors?  look in the console tab of the browser