You're looking at StableBuild's Deleted PyPI mirror - where we index all deleted packages from the Python package registry.

solvent
20.4.16

This version was deleted from PyPI around 2025-12-20. Installing fails with:
$ pip3 install solvent==20.4.16 ERROR: Could not find a version that satisfies the requirement solvent==20.4.16
View other deleted versions of solvent

Install through StableBuild

You can install this package from StableBuild's PyPI snapshots from before the version was deleted:
pip3 install \ -i https://YOUR_API_KEY.pypimirror.stablebuild.com/2025-12-19/ \ solvent==20.4.16
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Or, download files manually

And install manually via pip:
solvent-20.4.16-py3-none-any.whl (29.6KB)
solvent-20.4.16.tar.gz (14.8KB)