Board Thread:Bug Reports/@comment-27165287-20170702190258/@comment-27219153-20170704183022

That file isn't recognized as a .dat file once I download it. If it is for you, could you upload it somewhere that won't mess it up?

Alternatively you could try to copy another level.dat from another save, but if it works you will have chunk borders for all new terrain, and possibly a bunch of mismatched ids, as well as a few other differences.