Hi, I have this too. It only happens when I exit the game to the main menu and try to reload the game for a second time. For me restarting the game resolves this

Exceptions from the simulation thread mean that you have some obsolete mods or the savegame is corrupted. I cannot be more specific because the error message is completely general.

Loading with different savegames and disabling mods until it works are the standard procedures.

Notice that many mods do not support reloading from the in-game menu (different city) or the main menu (any city). So those kind of problems are expected.

Sorry for the very late reply.

Thanks for the reply, turns out my save file got corrupted and I had to start a new one.

Not sure which mods misbehave, but I've noticed this as well. So, just quit to desktop and reload. Takes a while (with my asset collection), but everything behaves nicely. Thale5, thanks for the info. Much obliged. :)

Greets from Asia, and I have also come across the same exception says "Simulation failed:Argument is out of range"(sometimes with parameter index?). It seems always appears when I quit from one game and load another, whether loding a save or a new map.

I thought it was mod conflict issue, and then when I disabled the "81 Tiles" mod, the exception doesn't appear anymore. So I think maybe the assets/mod reloading (or sharing?) part is somewhat uncompatible with the 81 Tiles mod.(maybe applied twice or sth)

Forgive my poor English (as I'm non-native speaker at all), and hope my issue can be useful for you. Thanks a lot :)

@Lanture "Argument is out of range" is a generic error message and basically means "something went wrong". In your case, however, the solution is a known one: 81 Tiles does not support reloading another map. Users of 81 Tiles must exit to Desktop before reloading.

@thale5 although seems to be a little bit inconvenient, thanks for your reply! :)

@Lanture Inconvenient, yes, but hardly my fault.

Dear friend, I have no more tears for this game. One upgrade, one city (60K civs and 1 year of work..) destroyed. The error handling is poor. Your mod is useful , but I wish to understand it better (I'm a professional sw developer, but in the wrong language, Abap ;) ). Did you have any suggestion (book, pdf,..) for my training in output log analysis? Now I see the "classic" error (Object reference not set...) followed by:
1. ..at RoadBaseAI.CanEnableTrafficLights (UInt16 nodeID, .NetNode& data) [0x00000] in <filename unknown>:0
2. [LSM] PoliciesPanel not initialized yet. Initializing at 1065917
3. at RadioPanel.AssignStationToButton (ColossalFramework.UI
4. Cannot set relative position without a parent Transform. (repeated)
5. LOD has no base:(repeated)

Maybe the problem is Transport Lines Manager or Procedural Objects.. ?
Thanks you again !
PS: My game is not upgraded, only mandatory patches.

@mirkozp The clues in output_log.txt are usually subtle. The above summary is even harder to analyze. The first serious looking exception is the best starting point. 1. definitely looks like one.

Maybe you already googled RoadBaseAI.CanEnableTrafficLights. It is a tough one. I'll take a look at game codes later today but don't expect too much.

@mirkozp If you get a null pointer exception from RoadBaseAI.CanEnableTrafficLights, then one of your road segments has a null NetInfo. NetInfo is the road model that describes the type of the road. It can be built-in, a road asset, or from Network Extensions 2. But now it is null.

Unfortunately the null check and try-catch is missing in that method. Obviously a dev oversight.

I was thinking I could write a small mod that adds the null check. I cannot guarantee it will solve all problems. Maybe the save is too badly damaged.

Your question about book or pdf: I suppose such short cuts are not possible. It's all about knowing the game codes (and some mod codes, too). Luckily the game is very accessible for mod activities: Visual Studio Community is free, .NET disassemblers are free and good, C# is nice to work with.

Thank you for the answer, your help is useful and I'll take a look at the links you mentioned. I still don't understand why a savegame becomes unstable at a certain point without upgrading. Did you think it could be possible a mod that bypasses the null exception, maybe translating the broken asset in a "default" or deleting it from the save (empty space is better than a crash) ? It should be a standard behavior imho..

@mirkozp Why a savegame becomes unstable: sw bugs, I guess. No-one has been able to pinpoint this one to any mod, so it could be a base game bug.

The problem here is the road segment(s) that have null NetInfo. The mod I was thinking about could either:
1. just avoid the null pointer crash, or
2. avoid the crash AND remove the faulty segment.

The problem with 1. is that the faulty segment may crash some later method during city setup.
The problem with 2. is that segment removal may confuse some later method.

As I cannot test the behavior here, I'll probably create a small mod that does 1.

@mirkozp
https://steamcommunity.com/sharedfiles/filedetails/?id=1620588636

If you try the mod, let me know what is in your output_log.txt.

Thank you! Yes , I have the Crossings mod unfortunately but I'll try the mod anyway..
cout << "I've started my C++ lessons"; ;)