Cannot access textmesh pro C#

I made a project with unity 2018.2.7f1 and it had textmeshpro allready installed, then i made few ui elements etc. then when i wanted to access text mesh pro via C# it didnt work.

It has always worked before but in this version it does not.
I have allready tried different version of textmeshpro and making a new project but nothing helps.

have you got on top of the script:

using TMPro;

?

If you upgraded your project, Your answer is here:

It’s a bug/glitch when upgrading.