"Error while loading a map"

[Chainlinc3]

I went to load my save from last night, got "An error occurred while loading a map.  See error log for more information"

Unfortunately, I can't find an error log anywhere, so this isn't really helpful.  I found an "output_log" in Rimworld's directory, which I put up here, but nothing jumped out at me as an error in that, so I suspect that isn't where I'm supposed to be looking.

I've sunk ~22 hours into this save so far, so I'd rather like to recover it.  Any guidance would be appreciated.

[milon]

Thanks for the log file!

The error may be related to RTMadSkills, which I assume it's a mod you're using. Moving to Mod Bugs, where you'll get better help.

[Chainlinc3]

Thanks for the pointer!  I have my save/configs backed up at this point, so I went ahead and tried removing the mod, but still encountered the same error (Well, with the added warning because now there's a mod mismatch, but same basic error screen).  RTMadSkills is a mod that changes skill decay, so if there's no in-game objects being added, I'd hoped that just removing it would resolve things neatly.  No dice there though.  I tried a few tweaks to see if I could finagle it into working, but that didn't work either, so I'll go poke the author on the Steam workshop and see if they know what's up.

Now that I have a better idea what I'm looking for though, I turned up this in the log as well:

Code Select Expand

Exception from asynchronous event: System.InvalidOperationException: SaveableFromNode exception: System.NullReferenceException: Object reference not set to an instance of an object
  at Verse.Thing.ExposeData () [0x00000] in <filename unknown>:0
  at Verse.ThingWithComps.ExposeData () [0x00000] in <filename unknown>:0
  at Verse.ScribeExtractor.SaveableFromNode[Thing] (System.Xml.XmlNode subNode, System.Object[] ctorArgs) [0x00000] in <filename unknown>:0
Subnode:
<thing Class="ThingWithComps"><def>Megascarab_Leather</def><id>Megascarab_Leather1779632</id><pos>(109, 0, 63)</pos><health>100</health><stackCount>2</stackCount></thing>
  at Verse.ScribeExtractor.SaveableFromNode[Thing] (System.Xml.XmlNode subNode, System.Object[] ctorArgs) [0x00000] in <filename unknown>:0
  at Verse.Scribe_Collections.LookList[Thing] (System.Collections.Generic.List`1& list, Boolean saveDestroyedThings, System.String label, LookMode lookMode, System.Object[] ctorArgs) [0x00000] in <filename unknown>:0
  at Verse.Scribe_Collections.LookList[Thing] (System.Collections.Generic.List`1& list, System.String label, LookMode lookMode, System.Object[] ctorArgs) [0x00000] in <filename unknown>:0
  at Verse.Game.LoadData () [0x00000] in <filename unknown>:0
  at Verse.SavedGameLoader.LoadGameFromSaveFile (System.String fileName) [0x00000] in <filename unknown>:0
  at Verse.RootMap.<Start>m__5A3 () [0x00000] in <filename unknown>:0
  at Verse.LongEventHandler.RunEventFromAnotherThread (System.Action action) [0x00000] in <filename unknown>:0

I'm not exactly an expert (or even a novice, to be honest), but I do remember having a weird entry in the debug log about megascarab leather when I started messing with mods.  I never figured out what precisely was causing it, but it also didn't appear to be causing a problem, so I never really worried about it.  Eventually the debug log stopped showing up every time I started the game, so I assumed something had updated to fix the problem.  But I do remember noticing that I had a few pieces megascarab leather after an infestation last night-- it stuck out to me because I thought it was weird that megascarabs have a hide you can make leather from, considering that they're insects and all.

Looking at the wiki now though, I don't see anything about megascarab leather existing.  But I also don't have any mods installed that I think should add it, so I'm not really sure what to make of all this.  Could this be part of the issue?

[Chainlinc3]

That turned out to be the problem, it looks like.  I ended up with megascarab leather somehow, but megascarab leather doesn't exist unless you're playing with Animal Hide Working (which I wasn't, but w/e), so the game was highly confused.  Not sure how it happened, but enabling Animal Hide Working so that the game knew what to do with the leather lets me at least load my game.

So, problem resolved.  Thanks for the help!

[milon]

Great!

I'm guessing that if you get rid of the megascarab hide (ie. Dev mode -> Destroy tool) and save the game, you could probably play without Animal Hide running.  But I'm glad it's working!

[Chainlinc3]

Honestly, I just sold it.  A textiles merchant showed up like two days later.

This is somewhat shifting the topic, but do you think it would be helpful to create a general troubleshooting guide to help people sort out mod problems like this?  I've been planning to learn modding and providing a sort of "for dummies" breakdown of stuff as I figure it out-- the tutorials on the wiki are helpful, but they read more like documentation (very dry, heavy on technical details, light on practical application), which is not the best way to get into a new project (at least for me).

Going from that (and feeling empowered once I figured out what I should be looking for in the logs), I thought it might be worthwhile to just do a similar "Idiot's Guide to the Debug Log," to help non-programmers identify (and hopefully resolve) the most common errors (assuming there ARE common errors).  But I also don't know how many people have those sort of issues and don't know how to fix them on their own.  If you think it would be helpful though, I'll try and do one once I get started.  I just figured I'd ask first, because there's no need to spend time and effort only to clutter the forum with stuff nobody needs (which is also why I'm asking here and hoping you see it rather than making a whole new thread, even though it's pretty off topic).

[milon]

I'm in favor of both of those topics being created.  They should go in the Modding \ Help subforum.  If you do make them, and if they're good quality (given your writing so far, that shouldn't be a problem) PM me and I'll sticky them.