DNN 7.4.2 2SXC (pre-upgrade) version 6.1.5
I installed 2SXC 08.11.00 and the installer told me there were errors (I didn't write them down, sorry). When I click "Return to site", the site is now throwing an error: Could not load type 'ImageResizer.Plugins.IAsyncTyrantCache' from assembly 'ImageResizer, Version=3.4.3.103, Culture=neutral, PublicKeyToken=null'.
So something is wrong with the ImageResizer DLLs. Maybe you already had Image-Resizer installed, or you probably had OTHER imageresizer DLLs (maybe caching helpers) which are still in the DLL folder, but now have a version conflict. Best remove all the ImageResizer DLLs which were not in the 2sxc-zip. If you really need them (maybe you had a water mark or something), get the corresponding version.
