This might be because you are using the association 'Module1.Object1Object2' at a location where the object 'Module1.Object3' is actually empty. Please look for locations where you use 'Module1.Object3' and specifically use the association 'Module1.Object1Object2' of that entity. Make sure you do an empty object check before using it. If it is empty log a message. That should allow you to localize it if it happens because of that in a microflow.
The cause could be because of entity access limitations or because a soap web service mapped incorrectly. Or because you are just passing empty 'Module1.Object3' object to a microflow.
I hope this helps.
So if I understand correctly you just see this error popping up in the logfile, and you're not able to trigger it yourself?
I do recognize the "The given member name 'Module1.Object1_Object2' has no corresponding member in this object of type 'Module1.Object3' at com.mendix.core.objectmanagement.MendixObjectImpl.getMember(MendixObjectImpl.java:231)' part, but only from when I'm manipulating MendixObjects in Java code when using the setMember syntax.
In this case my guess would be that the model file itself is broken, as there seems to be a schema defined with membernames that do not exist. I would think that removing and re-adding the page UI object (a reference list or something like that) that this shema is associated with would solve the issue, but that might be hard to do if you do not know which UI object to look for.
If this happens in a test environment, turning on TRACE logging for queries and query mapping might provide enough indication of what page this happens on.