gdb server problem when debugging

Hello,

I'm running Quartus12.0sp2 on a windows 11 computer and I want to use the nios 2 eclipse tools to build, run and debug.
Building and running works, but I encounter a problem with debugging via usb blaster.

I get the error message 'Error starting gdbserver - see console for details'.
If I start nios2-gdb-server.exe manually, I get the error message that two .dll files are missing:
'jtag_client.dll' and 'cygwin1.dll'. Both are present in some subfolders of c:/altera/12.0sp2.
This behaviour does not change when I start eclipse or gdbserver from the NiosII command shell.

Funnily, there is also a file 'nios2-gdb-server-fs2.exe' in the installation path, which seems to run. I tried tricking, by renaming this file into 'nios2-gdb-server.exe'. If I do so, the error message disappears, but the debugging process stops when trying to download the .elf file, at the step 'Launching: Stop processor if running'.

I found an old discussion about a similar problem in the forum:
Win7-Problem with NIOS-II debugger, can't start gdbserver | Altera Community - 224719
but there's also no clear solution for me.

Has anyone else encountered a similar problem?
Or can anyone explain what's the difference between 'nios2-gdb-server.exe' and 'nios2-gdb-server-fs2.exe'?
Or does know where I have to change a Path such that gdb-server can find the .dll files?

I'm quite lost and would appreciate any help.

Thanks,
Timo