Too many groovy classes were generated

Jasper Reports may throw this way generic error at times:

Too many groovy classes were generated. 
Please make sure that you don't use Groovy features such as closures 
that are not supported by this report compiler.


There is no definitive answer to this – it just seems to me like a blanket error for any syntax error, like:

  • $p instead of $P
  • $v instead of $V
  • bad UUID
  • incorrect XML attributes versus the version of your local JS server


I can’t suggest anything bullet proof to find the cause other than:

  • create a new empty file
  • paste in it the header and the footer plus a minimalist detail zone
  • test it out
  • .. and repeat