Hello guys

I have a dnn portal (5.2.3) with a third party newsletter module installed.

I know that this module is not fully compatible with 5.2.3 release of dnn, however, it was working fine first time i have updated the instance.

Now, when i enter the Newsletter page where module placed

I receive following error with current or new campaigns:

Exception in PageLoad() : Input string was not in a correct format.

It seems my campaigns not saved, and not runned on scheduled time.

Obviously something wrong, but i can't see any errors under Event Viewer, would anyone give me a clue on how to find what is going on wrong?

I can share my screen to those who are willing to help :)