Python syntax error not showing in output window

Hi,

I just updated from Revit 2026 to 2027 and from pyrevit 5.2.0 to 6.5.3.
When checking if my scripts needed any modifications to work with the new revit version I found that when there is a syntax error in my code it doesn’t get printed to the output window anymore.
The output window does show up but stays white.

I double checked with a different computer that has revit 2026 and pyrevit 5.2.0 with the same kind of syntax error and there it does get printed.

Perhaps something I need to change in the settings?

All of my scripts have the same layout where there is an A_main_script.py that handles the interface in B_interface.py and logic that is placed in C_some_name.py .

import os
import sys

current_dir = os.path.dirname(os.path.abspath(__file__))
sys.path.append(os.path.abspath(os.path.join(current_dir, "..")))
sys.path.append(os.path.abspath(os.path.join(current_dir, "..", "..")))


from MK import check_project_information
check_project_information.main()


from pyrevit import revit, output

import B_interface as interface
import C_Grid


def main():
    #Show the interface
    window = interface.GridWindow()

    # If data has been filled in and the ok button has been pressed proceed
    if window.should_run_script:
        with revit.Transaction("Create grids") as t:
            C_Grid.GridMaker(window).main()


if __name__ == "__main__":
    main()

    out_window = output.get_output()
    out_window.close()

How do you know there is a syntax error if it does not get printed?

Visual studio code indicates one of the functions can’t be found.
Upon further investigation it seems that errors in the A_main_script.py do print to the output window but errors in imported modules sometimes do and sometimes don’t show up.

C_Grid.GridMaker(window).main()

calls:

    def main(self):
        self.insert_input_in_project_information()
        self.remove_all_grids()
        self.create_new_grids()

Running it works but changing the last line so it’s incorrect gives varying results.
self.create_new_grids1() results in the correct error printed:

INFO: Deleted 47 old grid lines

ERROR [pyrevit.revit.db.transaction] Error in Transaction Context. Rolling back changes. | <type 'exceptions.AttributeError'>:GridMaker instance has no attribute 'create_new_grids1'

self.create_new_grids2() results in no error printed but program is stopped.

Any further changes to the line also result in no error getting printed.
When I remove the extra number at the end so it’s back to the original line the code immediatly just runs fine.

I’m quite certain I had the same in my A_main_script.py but I am unable to reproduce the missing prints when modifying this file.