i have system space added.

But if i have permission errors, this should also be when i make a new test customer. The only difference now is i have a hosting plan with only mail, made an addon who adds website to it.

So the original space as it was setup was with the same system service, and on the same server also resides the web server?

As the error is pretty straight forward that the hosting space can't find the path.

SolidCP logs the server/ service ID's for each user space created so if they get changed later to for example a virtual server on the hosting plan, the existing hosting plans don't change with it. they stay on the original hosting plan configuration.

With an addon it means the original server with the hosting plan should have all the services added in the addon, problems appear when the hosting plan server doesn't offer the services/ quotas selected in the addon, or when the hosting plan server / services was changed after the original space was created.

yes, everything is and was on the same server. I created the hostingplan without an iis site.

What you are saying is that the addon needs the same as the hostingplan, but extended with the extra rights ?

Addons is indeed extending the original hosting plan with addtional quota's

usually it's possible to have quota's 0 on the hosting plan and add for example 1 or 10 on addon without issues.

However i have heard that in certain services this acts bugy if it's not having any quota on the original hosting plan (i have never experienced this my self though).