Loading SD models throws "OSError Access Violation" if TEMP path contains non-ASCII chars (i.e. in username)

[A-Sverdrup]

Describe the Issue
Trying to load different SD models, koboldcpp-nocuda always fails with the following error:

Additional Information:

(using starter-pack-v2.kcppt as an example, but this also happened to every other image gen model I tried)

ImageGen Init - Load Model: C:\ai-models\z_image_turbo-Q4_0.gguf
With Custom VAE: C:\ai-models\ae.safetensors
With Custom Clip-1 Model: C:\ai-models\Qwen3-4B-Instruct-2507-Q4_K_S.gguf
Flash Attention is enabled
Backend assignment: "CLIP=CPU"

Swap to Diffusion Model Path:C:\ai-models\z_image_turbo-Q4_0.gguf
Try read vocab from C:\Users\╨Р╨╗╤М╤В\AppData\Local\Temp\_MEI201042/embd_res/qwen2_merges_utf8_c_str.embd
Traceback (most recent call last):
  File "koboldcpp.py", line 12536, in <module>
    main(launch_args=parser.parse_args(),default_args=parser.parse_args([]))
  File "koboldcpp.py", line 11068, in main
    kcpp_main_process(args,global_memory,using_gui_launcher)
  File "koboldcpp.py", line 11887, in kcpp_main_process
    loadok = sd_load_model(imgmodel,imgvae,imgt5xxl,imgclip1,imgclip2,imgphotomaker,imgupscaler,imgaudiovae)
  File "koboldcpp.py", line 2557, in sd_load_model
    ret = handle.sd_load_model(inputs)
OSError: exception: access violation reading 0x000000C3FF1F0000
[18420] Failed to execute script 'koboldcpp' due to unhandled exception!

[LostRuins]

Can you try a simple and small model like https://huggingface.co/koboldcpp/imgmodel/resolve/main/sdxs-512-tinySDdistilled_Q8_0.gguf

Does this work?

[A-Sverdrup]

No, same error

[LostRuins]

What if you select pure "use cpu" mode

[A-Sverdrup]

Same error again and again. Memory addresses and (this one number in square brackets) in traceback are different on every launch (even with the same model and same params), but the error is seemingly the same.

OSError: exception: access violation reading (some long hex address)
[(whatever this number means)] Failed to execute script 'koboldcpp' due to unhandled exception!

[A-Sverdrup]

Ok. I can't believe how stupidly simple the issue was.

C:\Users\╨Р╨╗╤М╤В\AppData\Local\Temp\_MEI201042/embd_res/qwen2_merges_utf8_c_str.embd

Note this broken encoding in the logs.

I created a user account with name "test" and it worked first try.

The issue is literally that whatever backend is there for loading SD models can't handle non-english (more probably more specifically non-ASCII) characters

[LostRuins]

Ahh yeah, that is confusing, of course it works for me then, since my username is english. Whoops. will fix it