VmModel - Error on Virtuemart Product filters for everyone except Super User

[coreit.gr]

Hi, I am issuing a strange error and I would like to ask for your help.

I have an eshop using on Joomla 3.9.16 and Virtuemart 3.6.0 and I have created user groups for its users.

I noticed that when we are in Virtuemart Products menu, only the Super Users can use the filters on top (Category Filter, Manufacturer Dropdown, Search Product, Date, Vendor, etc). All the other users get "0 Class 'VmModel' not found" when trying to use any of these. Not even the Administrators.

Is this a known bug or do you have any idea about what may be causing it? I couldn't find anything by searching in the forum.

Thanks a lot in advance.

[GJC Web Design]

Virtuemart 3.6.0 is very old

tested this on 3.6.10?

[coreit.gr]

Thank you for your reply.

I cloned the eshop to test it and updated to 3.6.10. The issue is still there...

Do you have any ideas on what may cause it and how can I fix it without having to assign all users to Super User group?

Thanks again.

[Milbo]

All the other users get "0 Class 'VmModel' not found" when trying to use any of these. Not even the Administrators.

This means that vm code is running, but vm was not loaded correctly. Sounds very strange for me. Maybe some permission stuff? Maybe this users are not allowed to use vm? What happens disabling any sef stuff?