Based on the error which references the “TextMeshPro-2017.2-1.0.56”, it looks like you ended up with the release for Unity 2017.2 instead of the release for Unity 2017.3.
See the following thread (sticky at the top of this forum) which contains a direct link to download the release for Unity 2017.3.
Make sure you review the Release notes and follow the upgrade instructions.