This sounds like goodness, but till we have unity builds working it's hard to accept any PR in this repo. Our efforts to unblock unity, mac and linux agents are across #1312 and #1345 PRs. We're all set except that unity in #1312 just hangs forever during the build. Can you help, @neuecc ?

Oh, I'll contact my companie's build engineer to resolve it.
Please wait for a next begining of the week.

Woot! I got the master branch build passing again in #1345 by a combination of code changes and getting a build agent running with the original Unity editor v2019.1.10f1 that has worked in the past.
We certainly should still update the version of unity we're using. I have an agent with 2020.3.17f1 ready to go. To move the pipeline to it, we just need to change
https://github.com/neuecc/MessagePack-CSharp/blob/ae79dc68e8fe4f03f4c19bd76e4d1f8bb7c5a984/azure-pipelines.yml#L38

like so

-      - UNITYVERSION -equals 2019.1
+      - UNITYVERSION -equals 2020.3

As the line to be changed was only just introduced in master, if you want to update as part of this PR, you'll have to merge master into your source branch.

@AArnott
I've merged orign/master, however Unity agent is stalled The agent request is not running because all potential agents are running other requests. Current position in queue: 1

@neuecc The build agent had shut down. I've restarted it and configured it to restart itself next time.

@AArnott thanks, all builds passed.