New Hybrid install on Windows 11

[Selur]

Still no luck, same pipe error message.

This is really strange,... I packed the content of Vapoursynth into a separate download, this way as a workaround you can take those files and put them in your Hybrid/64bit/Vapoursynth folder.
This way it should work, but it doesn't solve the problem why this is happening.

Maybe check the "Event Viewer", whether it contains any info about this.

Cu Selur