Does anyone have any ideas what could cause this kind of memory error in A2W 10.5.1:  

MemoryError: Exception ignored in thread started by: <bound method Thread._bootstrap of <Timer(Thread-10067461, initial 2862611264)>> Traceback (most recent call last):   File "/usr/acucobol1051/acutoweb/Tools/Python/lib/python3.8/threading.py", line 890, in _bootstrap     self._bootstrap_inner()   File "/usr/acucobol1051/acutoweb/Tools/Python/lib/python3.8/threading.py", line 918, in _bootstrap_inner     self._set_tstate_lock()   File "/usr/acucobol1051/acutoweb/Tools/Python/lib/python3.8/threading.py", line 913, in _set_tstate_lock     _shutdown_locks.add(self._tstate_lock) MemoryError:

Same code/program is been running fine in Acu 10.4.1 and 10.5.0 or at least no similar errors have been written in gateway.log . Now that more and more users have changes to 10.5.1 this memory error comes at least once a week.   

So far to cope with this we ended up scheduling Acu2web restart  first once and later twice a week.   

Good afternoon, @Janne Punki.

Can you please share more information about your environment?

What OS is used? 32 or 64 bit?
How much RAM is available?
How much RAM is being used by Python when this error happens?
How many users are connected simultaneously to ATW when this error happens?

You might be hitting the Python 32bit memory limitation of 4GB / 1024 threads.

Also - does AcuToWeb stops working when this error happens?