I need some help with this one as I'm running out of ideas.
What I have done -
1. Completely removed all other org installs to eliminate possible 'mixed version' issues. This includes the org bundled with emacs 25.1. Made no difference.
2. Try opeing an org file which does not have any source blocks. All works fine. Then tried opening the test file with a single source block and got the same error. The source block was not 'fontified'. Tried opening an org file with no source block, did an org-reload and then opened the test file with source block. Same error.
3. This 'looks like' a require load error or timing issue. After opening the test file and getting the error message I then kill the buffer and then open the file again for a second time, no error and the source block is now fontified. Makes me think that perhaps org is trying to fontify the buffer before some required library is loaded, reports an error, continues processing and loads the missing items and from then is OK when you load the next org file with a source block.
Question: How do you get this error to throw a backtrace? It seems toggle-on-debug has no effect. If I can get some additional information on when this error is being generated, I might be able to track this down further.
Tim