System.err.println() no longer printing to console

Hi folks,

in past (MPS 2020.X and later releases) i used System.err.println() in all language aspects to quickly write some information to the console, where i started MPS from. This was mainly for debugging purpose . I could use it in a generator macro or in a typsystem rule - no problem. 

However, the System.err's no longer get written to the console on MPS2023.3 - at least on the Mac installation. 

Does anyone has any ideas on that? How can i further investigate this behaviour?


Cheers for any hint,



Official comment

MPS now prefers using the logging language. The recommended way to insert trace messages or to log messages is described at



Thanks Vaclav - As always, thank you.  : ) 

I will refactor that .. 





Please sign in to leave a comment.