I have seen this issue before. The reason was that a file name contained a null-byte (ASCII 0). Please try renaming all of your blueprints. You will probably not see a null-byte there, but writing the file names again should fix it.
That was probably when you re-uploaded the site and the Toolkit was still missing. According to your error message from the first post, the Toolkit is loaded, so this can’t be it.
The Problems seems to be a Software that i use to mount my webserver’s directories to my mac os. I use mountain duck. It may be that this adds somewhat a null-byte to the name. When i reuploaded all blueprints via FTP, it worked.