Alright so here I am again.
On my way to study for the C3 certification I am setting up my environment for the T3 training module. One of the prerequisites for this module is to "Download and install the Visual Studio template set for Dynamicweb 9".
However when trying to install the DynamicwebTemplatesDW9VS2019.vsix from here https://doc.dynamicweb.com/downloads/other-downloads#4047, I am getting this very annoying error shown in the attached screenshots.
The path '/Output/ItemTemplates/CSharp/Dynamicweb%209/Ecommerce/Cart/AfterNewsletterSubscriptionValueIsChanged.csharp/AfterNewsletterSubscriptionValueIsChanged.csharp.vstemplate' defined in the C:\Users\RonniePoulsen\Downloads\DW\DynamicwebVSTemplatesDW9\DynamicwebTemplatesDW9VS2019.vsix file is not valid.
When trying to install again, the installer says, that the extension is already installed. But it is nowhere to find inside VS2019. I have then uninstalled the extension using the VSIXinstaller.exe, turned off my antivirus and firewall, and tried installing again but i'm still getting the same error. I can't figure out if the problem is in my local environment or if there is a problem with the VSIX provided by Dynamicweb.
Has anyone experienced this on their machine, or can anyone confirm that the actual VSIX works?
UPDATE: I have succesfully installed this extension on my other machine with almost exact same setup. So we can conclude that this is an issue with my local machine. What can cause this?