The given assembly name or codebase was invalid. (Exception from HRESULT: 0x80131047)

If you have this error and  you did all of those things:

• reinstalled DLLs,


• checked custom aspx if they reference any misspelled DLLs, 


• removed one by one all the custom solutions,


• ran the “SharePoint Products and Technologies Configuration Wizard”,


• thought “Let’s go for a lunch and then reinstall this machine”

Check the web.config Best thing would be to take it from other machine and compare with a diff tool.
Take a look at what was wrong in our case:


Lesson learned!