I'm using 2017-2018-2019. Still getting these errors....

Starting to think maybe wasting my money on Unity assets I get burned for and become unsupported (Pretty much right after I buy them and start using them), and my time on Unity itself is a bad idea. All I see is a software riddled by stupid issues, new versions of stead of just addressing the issues... then the new versions having the same issues and new ones... and utter-lack of backwards compatibility should almost be an embarrassment for Unity.... but still seem proud.

Thinking it's time to look for an Alternative, or just buy a real engine. In the end time and money would have been less.

And trying to use unity for anything bigger then mobile games is a fail, unless you want to spend 70% of your time looking at Unity in a "Not responding" state...

I'm still having the issue after upgrading to unity 4.5

This is happening still in 4.3.4f1

I am hitting the following issue on 4.3.3f1:
* Editor settings are set to ForceText
* ProjectSettings.asset has now been converted to binary

This is really annoying and prevents merging branches properly.

My workaround is to do as in: http://forum.unity3d.com/threads/210973-Could-not-serialize-text-file-projectsettings-projectsettings-asset-after-upgrade:

1. add this function to one of your Editor class

[MenuItem("Tools/PlayerSettingsPresets/ProjectSettings serialize Repair")]
public static void PlayerSettingsPresets_ProjectSettings()
{
PlayerSettings.SetScriptingDefineSymbolsForGroup(BuildTargetGroup.Unknown, "");
AssetDatabase.Refresh(ImportAssetOptions.ForceUpda te);
}

2. run it

3. force a save of the ProjectSettings. I usually do this by: open the BuildSettings, toggle off/on one of the scene in the list of scenes, and force a save by doing CTRL-S

Fact is that bagelbaker's workaround doesn't work on my setup. It does appear to fix to the problem, but the fix is only temporary: as soon as you change something (beats me if I know what "something" triggers the bug) the projectsettings file becomes binary again.

I don't know why this is marked as resolved, but bagelbaker has posted a workaround: http://forum.unity3d.com/threads/210973-Could-not-serialize-text-file-projectsettings-projectsettings-asset-after-upgrade?p=1420442&viewfull=1#post1420442

It says "fixed", but in which version? The bug is still present in 4.3.3f1 and it's not listed as fixed in the release notes of 4.3.4. I'm not going to upgrade to 4.3.4 just to check that, because upgrading Unity (even minor upgrades!) is not always hassle-free (this bug is an example).

Worth noting that when I check back in the version control history, this file was changed from a text to a binary version during the 4.2 -> 4.3 upgrade, even though the project is and always has been set to use text serialisation for assets.

The bug description says it's not a regression, but I'm pretty sure it is, which should argue for a higher priority.

I can confirm this here: large project, Forced Text used for serialisation, and when other people make changes to the file that I pick up through source control, it throws this error and my local file is saved. The file is definitely binary. It does however seem to keep those external changes though, so it's loading the changed settings just fine, then decided they need re-saved, and writing something subtly different out after putting this error out to the console.