Hey @splaisan,
We have seen a few cases of this popping up since the 2026.1 release - it appears as though there is some compatibility issue between the latest version of conda (26.1.1) and our 2026.1 release environment files. We've made some pretty substantial updates to our environment files in preparation for the 2026.4 release which we are hoping will resolve this issue but in the meantime our current workaround/recommendation is to downgrade to conda 25.11.1, which is the latest version without any compatibility issues. You can roll back your version of conda with the following command:
conda install -c conda-forge conda=25.11.1
Once that's been downgraded, you should be able to re-install QIIME 2 2026.1 without any issues.
Cheers 