More notes:

First run: No exception on load, and at start, but some point there after in the log (but nothing on screen to indicate a problem) during the 2 minutes. 

B1146.2 -- Nullable object must have a value.
Exception: Nullable object must have a value.
Stack Trace:    at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Nullable`1.get_Value()
   at Command_Core.Module_Unit.Unit.()
Call Stack & Error details: 
Error at 200320, Nullable object must have a value.
---

Of course this isn't the same exception that OP reported.


b1146_2 Second run:
(paying more attention trying to catch exact timing of first): no problem in-game but exceptions in the log generated.

At in-game time around 12:15:27 zulu:
12:10:34(realtime) B1146.2 -- Collection was modified; enumeration operation may not execute.
Exception: Collection was modified; enumeration operation may not execute.
Stack Trace:    at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Collections.Generic.Dictionary`2.Enumerator.MoveNext()
   at Command_Core.Scenario.()
Call Stack & Error details: 
Error at 200053, Collection was modified; enumeration operation may not execute.
---
fwiw that was about 6 realtime seconds after the last autosave.


b1147_2 First run: 
Exception during first 9 in-game seconds (but not upon load or side selection or before pressing play or in first second of play, sorry went to get coffee but had checked snaketail log monitor just before heading off as it got started so I don't know exact in-game time). 

-- B1147.2 -- Object reference not set to an instance of an object.
Exception: Object reference not set to an instance of an object.
Stack Trace:    at Command.MainForm.()
Call Stack & Error details: 
Error at 200195, Object reference not set to an instance of an object.

At in-game time around 12:14:20z -\+ a second 
1:45:34 PM -- B1147.2 -- Collection was modified; enumeration operation may not execute.
Exception: Collection was modified; enumeration operation may not execute.
Stack Trace:    at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Collections.Generic.Dictionary`2.Enumerator.MoveNext()
   at Command_Core.Scenario.()
Call Stack & Error details: 
Error at 200053, Collection was modified; enumeration operation may not execute.
---
This was recorded approx 7 realtime seconds after autosave last modified timestamp of 1:45:41

At in-game time 12:15:02z  (duplicate of the above one)

2:10:08 PM -- B1147.2 -- Collection was modified; enumeration operation may not execute.
Last autosave modified time was 2:09:59.

b1147_2 Second run:  
At in-game time around 12:14:14z
6/14/2020 3:09:34 PM -- B1147.2 -- Collection was modified; enumeration operation may not execute.
Exception: Collection was modified; enumeration operation may not execute.
Stack Trace:    at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Collections.Generic.Dictionary`2.Enumerator.MoveNext()
   at Command_Core.Scenario.()
Call Stack & Error details: 
Error at 200053, Collection was modified; enumeration operation may not execute.
last autosave modified time 3:09:16

At in-game time around 12:14:17z
6/14/2020 3:19:54 PM -- B1147.2 -- Collection was modified; enumeration operation may not execute.
Exception: Collection was modified; enumeration operation may not execute.
Stack Trace:    at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Collections.Generic.Dictionary`2.Enumerator.MoveNext()
   at Command_Core.Scenario.()
Call Stack & Error details: 
Error at 200053, Collection was modified; enumeration operation may not execute.
last autosave modified time 3:19:36.

Idk if it matters but I did clear the msglog on loadup all times before hitting play. On the second pass with 1146_2 and for 1147_2 tests I had disabled sounds, and moved the map view south to an inactive area to help ever so slightly with the crawl speed. All four runs I disabled all my usual show-this-show-that display options (other then for the first couple seconds of round 1 where they were enabled, but exception happened well after that).

I did not test that any of the generated autosave would actually load, I did try to watch the timestamps on them to coordinate with the exception log timing though nothing appeared to exactly coordinate. I noticed the logs are almost double the size in the 1147_2 runs not sure what to make of that other than maybe more reporting now in 1147 for weapons involved. 

os: srv2008r2
