I got this when updating from 2018.2 to 2019.3 It seems somewhat related to new lines that the new YAML parser handles differently. My fix was to simply rebuild affected assets, so it wasn't catastrophic. But, I can see it breaking projects heavily if not addressed. I tested on a4 and a5 and submitted a bug on 08/06. Case # is 1161290 I'm posting here to get some extra visibility, as QA has yet to reply to the bug report. Saw someone else mentioning this here: https://forum.unity.com/threads/i2-...olution-for-unity.231226/page-15#post-4601569 I2 localization bakes strings into an scriptable object, so it is a good candidate to trigger this bug. My bug report includes a small test project with an asset extracted from my own project. The issues reproduces every time.