In most cases, in my experience, the error is due to a path or dataset name that cannot be used in a part of the geoprocessing chain. There are more obscure issues like funny characters in an Excel sources, but that is another story.
Check the file path, file names, layers names, etc for spaces or non-standard characters. Base letters (no Ä for example), numbers or '_' is all I use.
Check the filename + path lengths of inputs & outputs. They could be too long cumulatively.
I will create a FGDB called 'Test' in a shallow folder e.g. c:\gis_test\ and with a test dataset test1.shp, image1.tif, etc and see if I can get the process to work.
You can then iterate to find the offending item and fix it.
If this doesn't fix it, check the random names Pro created for the project and replace them with toolboxes, folders, etc that YOU create.
Be methodical and I'm sure you'll get it sorted.
