Command /home/docs/checkouts/readthedocs.org/user_builds/bio2bel-kegg/envs/latest/bin/python -m pip install --upgrade --upgrade-strategy eager --no-cache-dir /home/docs/checkouts/readthedocs.org/user_builds/bio2bel-kegg/checkouts/latest[docs] failed: Processing /home/docs/checkouts/readthedocs.org/user_builds/bio2bel-kegg/checkouts/latest Preparing metadata (setup.py): started Preparing metadata (setup.py): finished with status 'done' Collecting pybel<0.16.0,>=0.15.0 Downloading pybel-0.15.4-py3-none-any.whl (383 kB) Collecting click Downloading click-8.0.3-py3-none-any.whl (97 kB) ERROR: Could not find a version that satisfies the requirement bio2bel[web]<0.5.0,>=0.4.0 (from bio2bel-kegg[docs]) (from versions: 0.0.1, 0.0.2, 0.0.3, 0.0.4, 0.0.5, 0.0.6, 0.0.7, 0.0.8, 0.0.9, 0.0.10.dev0, 0.0.10, 0.0.11.dev0, 0.0.11, 0.0.12.dev0, 0.0.12, 0.0.13.dev0, 0.0.13, 0.1.0.dev0, 0.1.0, 0.1.1.dev0, 0.1.1, 0.1.2.dev0, 0.1.2, 0.1.3, 0.1.4, 0.1.5, 0.2.0, 0.2.1, 0.3.0) ERROR: No matching distribution found for bio2bel[web]<0.5.0,>=0.4.0

Problem in your project's configuration. Invalid configuration option "build.os": os not found