During this migration server PC itself, Windows OS , and Cygwin version have been changed up to most recent ones.
However we have faced with same error described in http://smstools3.kekekasvi.com/topic.php?id=557&page=2 :
Error appeared for the first time after 3 weeks of working.
I have reinstalled previously accepetd version : 3.1.14-VVV-3.
( it worked fine for us on old server ).
Also I have found that such error appear not only on Cygwin : http://smstools3.kekekasvi.com/topic.php?post=5006#post5006.
Keke, could you please include fixes of 3.1.14-VVV-3 into main smsd verison ?
It proved great stability during few years..
Thank you very much for your support!