I ran into a problem with a 34 character long internal field name (cb_custom_email_after_banner_html) on a editor text area field. The field created and displayed fine, however, it would not update the database.

Surmising the most likely cause of the problem was mine since CB is rock solid, I could think of nothing else than the internal name being too long and causing some issues that didn't produce an error but didn't work either.

I shortened the internal name to 25 and the field updated with no problem.

What is the longest internal field name we can use?

Obviously, validating the length of the name field or setting a max length for input might be a good idea; not critical for sure but perhaps helping avoid a problem.

Thanks!

That certainly makes sense and I agree. Limiting the field input to the same 50 characters would be helpful so people don't do what I did and go over the limit. I'm guessing that you've done that already.
No matter, thanks for taking a good look at this and explaining the rationale and limitations. Much appreciated.