It is a common problem that TexnicCenter fails to call Adobe Acrobat Reader as the pdf viewer:
[DocOpen("%bm.pdf")]... Cannot execute the command.
I know that this can be fixed by changing the name of the "server" in the viewer output profile. This is how I have fixed it every time before. Currently I have it as "acroviewR21", which has worked this year until today. Usually it can be fixed just by updating the year, but since it is still 2021 (as is my version of acrobat reader DC), I am really not sure what to do. I have tried various permutations of the capitalization to no effect. I have tried making it 22 with no effect.