As the blog post says: "Error: Syntax Error".

Helpful error messages have not been my experience.

Syntax errors are suboptimal. They are usually reported at correct location and it's relatively easy to spot them.

On the other hand type error messages are simply awesome.

Generally auto generated parsers have huge problems with error recovery (bailing out quickly) and reporting. They usually exceed in performance however. I’m not sure where OCaml stands.

They do not want to change the parser but the parser generator.

One issue is mentioned in the blog post:

The days of Error: Syntax error. may be numbered