git clone / git push: 'remote: Repository not found. fatal: repository ... not found' (or ERROR: Repository not found over SSH) even though the repository exists. How do I fix it?

Cause: GitHub (and other hosts) answer 'Repository not found' both when the repository truly doesn't exist and when your credentials can't see it, so a private repository you don't have access to looks missing. Common reasons: a typo or wrong owner in the URL, or the repo was renamed or moved; git is using cached credentials for a different account (a work vs personal account, an old token in the OS credential manager); the token lacks access to that repository or organization (fine-grained token without the repo selected, or the org requires SSO authorization); an SSH key belongs to a different account; or you're not a collaborator yet. Fix: 1. Check the URL: git remote -v, and open the same URL in a browser while logged in to the account you expect. 2. See which identity git uses: for SSH, ssh -T git@github.com prints the account; for HTTPS, check the OS credential manager (Windows Credential Manager, macOS Keychain, or git credential-manager) for stored github.com entries. 3. Replace stale credentials: remove the github.com entry from the credential store (or run git credential reject with the host), then authenticate again with the right account, using a token that has access to that repository (and SSO-authorize it for organizations that require SSO). 4. Using several accounts? Use separate SSH keys with host aliases in ~/.ssh/config, or per-repository credential settings, so each repo uses the right account. 5. If the repo moved or was renamed, update the remote: git remote set-url origin <new-url>. 6. If you simply don't have access, ask the owner to add you or your team. Verify: git ls-remote origin lists refs without errors, then retry the clone or push. Sources: https://docs.github.com/en/repositories/creating-and-managing-repositories/troubleshooting-cloning-errors https://git-scm.com/docs/gitcredentials