# SlicerPreview: python default encoding is troublesome. Is it generally observed?

**URL:** <https://discourse.slicer.org/t/slicerpreview-python-default-encoding-is-troublesome-is-it-generally-observed/43826>\
**Category:** Feature requests\
**Created:** [July 23, 2025, 3:38pm UTC](https://discourse.slicer.org/t/slicerpreview-python-default-encoding-is-troublesome-is-it-generally-observed/43826 "2025-07-23T15:38:50Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![chir.set](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/chir.set/32/66982_2.png) [@chir.set](https://discourse.slicer.org/u/chir.set)\
**Post date:** [July 23, 2025, 3:38pm UTC](https://discourse.slicer.org/t/slicerpreview-python-default-encoding-is-troublesome-is-it-generally-observed/43826/1 "2025-07-23T15:38:51Z")

</div>

Hello,

On starting SlicerPreview 33801 on Arch Linux, a very long list of decoding errors related to python appears in stdout. The last ones are as below:

```auto
  File "/opt/programs/Test/Slicer-5.9.0-2025-07-22-linux-amd64/lib/Python/lib/python3.12/site-packages/numpy/testing/_private/utils.py", line 1387, in check_support_sve
    output = subprocess.run(cmd, capture_output=True, text=True)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/programs/Test/Slicer-5.9.0-2025-07-22-linux-amd64/lib/Python/lib/python3.12/subprocess.py", line 550, in run
    stdout, stderr = process.communicate(input, timeout=timeout)
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/programs/Test/Slicer-5.9.0-2025-07-22-linux-amd64/lib/Python/lib/python3.12/subprocess.py", line 1209, in communicate
    stdout, stderr = self._communicate(input, endtime, timeout)
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/programs/Test/Slicer-5.9.0-2025-07-22-linux-amd64/lib/Python/lib/python3.12/subprocess.py", line 2153, in _communicate
    stdout = self._translate_newlines(stdout,
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/programs/Test/Slicer-5.9.0-2025-07-22-linux-amd64/lib/Python/lib/python3.12/subprocess.py", line 1086, in _translate_newlines
    data = data.decode(encoding, errors)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc2 in position 12: ordinal not in range(128)
decoding with 'ANSI_X3.4-1968' codec failed
Switch to module: "Volumes"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
NameError: name 'loadSlicerRCFile' is not defined
Switch to module: ""
Switch to module: ""

```

Slicer is not usable: no view is available in the default layout though one can be selected, python modules are not loaded, slicerrc is not loaded… nothing python is available.

If this [hack](https://discourse.slicer.org/t/slicerrt-built-from-source-cannot-start/43792/12) is applied, an expected running Slicer is observed.

I wish to know:

- if this is observed on other Linux distributions
- if this is observed on non-Linux operating systems.

Thank you.