My miniconda3 installation is screwed up. Reinstall? something else?

Windows 10. Any attempt to use the conda application (even conda --version) begets a very long error traceback starting with

Traceback (most recent call last):
File “C:\Users\UserName\miniconda3\lib\site-packages\conda\”, line 16, in call
return func(*args, **kwargs)

and ending with

File “C:\Users\UserName\miniconda3\lib\site-packages\urllib3\”, line 292, in BaseHTTPResponse
DECODER_ERROR_CLASSES += (brotli.error,)
AttributeError: module ‘brotli’ has no attribute ‘error’

I started having a lot of problems when I started using conda-forge. I can’t remember exactly what I did, but for sure I had conda-forge primary in one or more envs, and the default in others. Is that a bad thing to do? Should all envs point to the same channel?

The other thing that I’ve done, sometimes accidentally, sometimes on purpose, is run ‘conda updata conda’ in various environments. Is that a mistake? Should conda be updated in every env? Just base?

I considered re-installing miniconda, but I don’t know if that would delete my existing environments. Is re-installing a good idea? If so, how to re-install while protecting my environments.?


Hi @GAPajer,

When you uninstall Miniconda, this will also remove all the environments you have under " “C:\Users\UserName\miniconda3\envs". Before uninstalling, I would make a backup of this folder so you can copy it back after your reinstall.

There’s nothing wrong with using “conda-forge” in certain environments and “defaults” in others. I would advise against mixing the two in a single environment though. So, it would probably be best to keep you “base” environments tied to “defaults”. It you would like to just use conda-forge, there is actually a “miniforge” installer available (GitHub - conda-forge/miniforge: A conda-forge distribution.).

You should only have to update conda in your base environment.

Hope this helps you!

Seems like it’s a bug. Another user seems to have the same problem:

Hi @GAPajer,
I had the same problem & fixed it by reinstalling brotli via pip, yet that “solution” does not work for everyone, see: StackOverflow 61881121.