Why am I getting Unknown error in line 1 of pom.xml?

Question

Getting unknown error at Line 1 in pom.xml in Eclipse IDE. It was working fine till yesterday, but all of a sudden after updating my project from master and aft

Answer 1

I was getting same error in Version 3. It worked after upgrading STS to latest version: 4.5.1.RELEASE. No change in code or configuration in latest STS was required.