Fix for game crashing when playing on older versions (For probably most people)

[BI0ck]

If you play a version after 1.31 and try to go back to 1.30 or earlier you may find that the game crashes when you select a nation and play as them. The main advice I've seen so far is to go into your game files and delete everything in the Europa Universalis folder in Documents/Paradox Interactive. This works, but is clunky because you have to go and change all of your settings back, and as well you need to backup all your saves unless you want to lose them.
Eventually, I got fed up with this process and I figured out the cause of the problem.

The main reason these crashes occur is because 1.31 added a few new alerts, including the annoying "an enemy is naval invading" and "an enemy is occupying your land" alerts which I tend to disable because I dont like seeing them pop up and then disappear over and over again.

Unfortunately, if you disable an alert and then go back to a version that does not have the alert, the game gets confused and decides to crash. There's an easy fix though, just go to the latest version and un-disable the alerts (or go into settings.txt and remove the disabled_alerts section if you dont want to load the game0

This might not fix every crash, but I hope that anyone who has the same problem that I had can see this and hopefully it will fix it.

 

[CoolSpin]

How on earth did you track a crash down to this specific tiny thing?? What clues did you find to narrow it down? Good job!

 

[BI0ck]

How on earth did you track a crash down to this specific tiny thing?? What clues did you find to narrow it down? Good job!

I knew that the crash was fixed by deleting something in the Europa Universalis 4 folder, since I tried it after asking how to fix the crash.

So, I went and deleted things individually in the folder, until I found the thing that caused it to crash.
Eventually, I noticed that the settings.txt file was causing this. I don't want to delete my settings every time I want to play an outdated mod, though, so I went and copied my settings.txt file, then launced the game in 1.30 to get a unaltered settings file.
I compared these two and the only big difference (i.e. not different sound volumes, etc.) was that one had disabled alerts and the other didnt. I realized then that 1.31 added those alerts I disabled, so I connected the dots and figured out that if you disable an alert that doesnt exist in an older patch, then the game crashes.