error message when opening R project

Does anyone have any suggestions on how to solve this problem?

Problem: I can't reopen any R projec (.Rproj). When I try i get this error message:

Warning message:
In normalizePath(path.expand(path), winslash, mustWork) : path[1]="C:/Users/Andr�sLagerl�f/Documents": Det går inte att hitta sökvägen

The last part "Det går inte att hitta sökvägen" is in Swedish and, tanslated to Enlish it means that "the search path can not be found"

I have installed R directly under the root folder C:\R, because I have previously run into trouble which I belive is because my name and my users folder is "Andrés Lagerlöf " and that the non Enlish characters causes problems.

In RStudio / Global options in the option for R sessions, under "Default working diriectory (when not in a project)" I have set "C:/R"

System: I'm using a Windows computer.

Kind regards,