We came across this bug while testing our upgrade for Rhino 8. If you are running Rhino 8 in NET8.0 mode with the SetDotNetRuntime command and try to enable the PDF Export plugin, you get the following error.
If you close Rhino, re-open it, and dynamically try to load the PDF Exporter (for example by printing a page) it will load it correctly. After that it doesn’t seem to happen again. If you have it use NetFramework this does not happen.
If you want to replicate this issue, make sure to delete the local temp files in AppData\Roaming\McNeel\Rhinoceros\8.0 and delete the Rhino 8 registry node for the current user.
A side-effect from this bug is that Rhino.FileIO.FilePDF.Create() returns null. It took a while to figure out why our testing was encountering this bug.
When you run _SetDotNetRuntime and change the .NET runtime you will have to restart Rhino before doing anything else like loading plug-ins anyway. The command will tell you to do so with a modal dialog box. From the sound of it you are not restarting Rhino after you have run the command.
I thought that was the case too, but it does not appear that restarting Rhino solves it. I tried it on 8.19 and 8.24 as well since the newer ones start with NET8.0 enabled by default. No luck there either. For 8.24 I did a full uninstall and re-install just to make sure there wasn’t something else causing this.
