ReWrite TextFile fires I/O Error 50

Hi

Delphi 10.1: I sometimes have the error 50 when I try to create a file:

var
    f : TextFile;
begin
  ReWrite(f,'\\myServer\anyPath\myFile.txt');  //Error 50 if the file exists
end;

I also tried to delete the file before if it exists. That is also impossible. Deleting in the explorer works and the I can ReWrite it. This error occurs in programs that never had problems. I think it has something to do with a Windows-Update. How can I solve this?

Thanks, Peter