It happens when you start SteamCloud's save game and turn off pause.

build: U52-626616-SC
Mod v.1.0.16.0
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Assert failed: openOrderCount invalid

at UnityEngine.Debug.LogError (System.Object message) [0x00000] in <8d0cda731089431c9d3668ae59fa9ace>:0
at Debug.LogError (System.Object obj) [0x00000] in <6ada15b5db02463a801f4ecc03190c6e>:0
at Debug.Assert (System.Boolean condition, System.Object message) [0x00000] in <6ada15b5db02463a801f4ecc03190c6e>:0
at ComplexFabricator.ComplexFabricator.StartWorkingOrder_Patch2 (ComplexFabricator , System.Int32 ) [0x00000] in <fb8aceaac76a41e5933b005c0166651a>:0
at ComplexFabricator.RefreshAndStartNextOrder () [0x00000] in <fb8aceaac76a41e5933b005c0166651a>:0
at ComplexFabricator.Sim1000ms (System.Single dt) [0x00000] in <fb8aceaac76a41e5933b005c0166651a>:0
at SimAndRenderScheduler+Sim1000msUpdater.Update (ISim1000ms updater, System.Single dt) [0x00000] in <6ada15b5db02463a801f4ecc03190c6e>:0
at UpdateBucketWithUpdater`1[DataType].Update (System.Single dt) [0x00000] in <6ada15b5db02463a801f4ecc03190c6e>:0
at StateMachineUpdater+BucketGroup.AdvanceOneSubTick (System.Single dt) [0x00000] in <6ada15b5db02463a801f4ecc03190c6e>:0
at StateMachineUpdater.AdvanceOneSimSubTick () [0x00000] in <6ada15b5db02463a801f4ecc03190c6e>:0
at Game.SimEveryTick (System.Single dt) [0x00000] in <fb8aceaac76a41e5933b005c0166651a>:0
at Game.Update () [0x00000] in <fb8aceaac76a41e5933b005c0166651a>:0
Build: U52-626616-SC

Seems to come from Kiln. Remove it from the config file.

I have the same issue and it's not the Kiln. I removed it from the config file and it's still happening.

Assert failed: openOrderCount invalid

at UnityEngine.Debug.LogError (System.Object message) [0x00000] in <82f243aab18c4f32918da2df41974365>:0
at Debug.LogError (System.Object obj) [0x00000] in <5dfe0ae6d45544628b5ae53433ea03d4>:0
at Debug.Assert (System.Boolean condition, System.Object message) [0x00000] in <5dfe0ae6d45544628b5ae53433ea03d4>:0
at ComplexFabricator.ComplexFabricator.StartWorkingOrder_Patch2 (ComplexFabricator , System.Int32 ) [0x00000] in <a68254e14f8f4e0b99360e84d2e9b774>:0
at ComplexFabricator.RefreshAndStartNextOrder () [0x00000] in <a68254e14f8f4e0b99360e84d2e9b774>:0
at ComplexFabricator.Sim1000ms (System.Single dt) [0x00000] in <a68254e14f8f4e0b99360e84d2e9b774>:0
at SimAndRenderScheduler+Sim1000msUpdater.Update (ISim1000ms updater, System.Single dt) [0x00000] in <5dfe0ae6d45544628b5ae53433ea03d4>:0
at UpdateBucketWithUpdater`1[DataType].Update (System.Single dt) [0x00000] in <5dfe0ae6d45544628b5ae53433ea03d4>:0
at StateMachineUpdater+BucketGroup.AdvanceOneSubTick (System.Single dt) [0x00000] in <5dfe0ae6d45544628b5ae53433ea03d4>:0
at StateMachineUpdater.AdvanceOneSimSubTick () [0x00000] in <5dfe0ae6d45544628b5ae53433ea03d4>:0
at Game.SimEveryTick (System.Single dt) [0x00000] in <a68254e14f8f4e0b99360e84d2e9b774>:0
at Game.Update () [0x00000] in <a68254e14f8f4e0b99360e84d2e9b774>:0
Build: U53-643502-SC

Okay. I will take a note and try to figure out a workaround. But since it's so hard to test, I can't promise a fix.

You might recover by loading without the mod, (maybe unpausing a couple seconds,) saving, and re-enabling the mod. Let me know your experience.

That worked! Hopefully that also helps you identify the bug knowing that's a workaround.

I already suspected that saving is the issue. But it happens so rare, I did not encounter it myself. I am still puzzled why it happens at all.

Loooooooooooooove your mod. Number 1 mod of the 58 I have enabled.
I also had a crash with an autosave hick-up. Disabling and later enabling the mod fixed it.

NullReferenceException
at (wrapper managed-to-native) UnityEngine.Component.GetComponentFastPath(UnityEngine.Component,System.Type,intptr)
at UnityEngine.Component.GetComponent[T] () [0x00021] in <82f243aab18c4f32918da2df41974365>:0
at PipedEverything.ConduitConsumerOptionalSolid.CapacityForElement (Pickupable element) [0x0001c] in <a434f07c9d2f4dec938c17cc3412c6fc>:0
at PipedEverything.ConduitConsumerOptionalSolid.ConduitUpdate (System.Single dt) [0x00057] in <a434f07c9d2f4dec938c17cc3412c6fc>:0
at SolidConduitFlow.Sim200ms (System.Single dt) [0x0010e] in <a68254e14f8f4e0b99360e84d2e9b774>:0
at Game.StepTheSim (System.Single dt) [0x009b0] in <a68254e14f8f4e0b99360e84d2e9b774>:0
at Game.UnsafeSim200ms (System.Single dt) [0x000b0] in <a68254e14f8f4e0b99360e84d2e9b774>:0
at Game.SimEveryTick (System.Single dt) [0x00054] in <a68254e14f8f4e0b99360e84d2e9b774>:0
at Game.Update () [0x00082] in <a68254e14f8f4e0b99360e84d2e9b774>:0

Well, that's a different issue. There was an object that did not have its components (probably PrimaryElement). That's illegal. I wonder how that got generated...
I can make a null check there, but it might still fail at other points. Really weird.

Wait a minute. I had the crash later on again and saw I was putting oxylite into Wood burners and Wood Heaters via conveyor rail. That probably made the crash.