Error map
not possible to fast-forward fatal: Not possible to fast-forward, aborting.
Git · layer 7, Build & delivery
Centre: this error. First ring: errors it is linked with (7). Outer ring: what those are linked with. Colours show the layer of a request each error belongs to. Click any dot to re-centre the map on it; hover to follow its connections. The centre dot opens the error page.
Directly related (7)
hint: You have divergent branches and need to specify how to reconcile them.
Git 2.27+ asks you to choose merge, rebase or fast-forward-only when local and remote both have new commits.
Git: CONFLICT (content): Merge conflict in file — Automatic merge failed
Both branches changed the same lines; Git needs you to choose the final content before completing the merge/rebase.
error: Your local changes to the following files would be overwritten by merge
git pull/merge would modify files you’ve changed but not committed.
fatal: You have not concluded your merge (MERGE_HEAD exists). Please, commit your changes before you merge.
A merge is still in progress — conflicts were resolved (or not) but not committed.
fatal: a branch named 'x' already exists
You tried to create a branch whose name is already taken locally.
fatal: Authentication failed for 'https://github.com/x/y.git/'
HTTPS authentication to the Git host failed — wrong or expired credentials, or a password used where a token is required.
fatal: ambiguous argument 'HEAD': unknown revision or path not in the working tree.
The repository has no commits yet (or the ref doesn’t exist), so HEAD can’t be resolved.
Two steps away (21)
HTTP 413 Content Too Large (Request Entity Too Large)
The request body is bigger than the server is willing to accept — usually a file upload over the configured limit.
OAuth Error: redirect_uri_mismatch
The redirect URI in your OAuth request doesn’t exactly match one registered for the client in the provider’s console.
WordPress: Error Establishing a Database Connection
WordPress can’t connect to its MySQL/MariaDB database with the credentials in wp-config.php, or the database server is down.
Git: ! [rejected] … (fetch first) — error: failed to push some refs
The remote branch has commits you don’t have locally, so Git refuses to overwrite them. Pull (merge or rebase) first, then push.
Git: fatal: refusing to merge unrelated histories
The two branches have no common ancestor — typically a local repo and a remote that were both initialized separately.
fatal: It seems that there is already a rebase-merge directory, and I wonder if you are in the middle of another rebase.
A previous rebase is still in progress (or was interrupted).
error: The following untracked working tree files would be overwritten by checkout/merge
Untracked local files have the same paths as files coming from the other branch.
error: cannot pull with rebase: You have unstaged changes. Please commit or stash them.
A rebase (or pull --rebase) needs a clean working tree.
error: Your local changes to the following files would be overwritten by checkout
Switching branches would discard uncommitted changes in files that differ between branches.
fatal: Unable to create '.git/index.lock': File exists. Another git process seems to be running in this repository
A lock file from another (or crashed) Git process blocks this command.
error: object file .git/objects/x is empty / fatal: loose object is corrupt
The local Git object database is corrupted — usually after a crash, disk full or sync tool interference.
warning: There are too many unreachable loose objects; run 'git prune' to remove them.
Git’s automatic garbage collection found many unreachable objects and is asking you to prune.
You are in 'detached HEAD' state.
HEAD points at a commit instead of a branch, so new commits won’t belong to any branch.
error: pathspec 'x' did not match any file(s) known to git
Git couldn’t find the file or branch name you referenced.
error: src refspec main does not match any
You pushed a branch name that doesn’t exist locally — usually no commits yet, or the branch is called master not main.
Git: Permission denied (publickey). fatal: Could not read from remote repository.
SSH authentication to GitHub/GitLab/Bitbucket failed — no key, wrong key, or the key isn’t added to your account.
Azure AD (Entra ID): AADSTS700016 Application not found in the directory
The client ID in your sign-in request doesn’t exist in the tenant you’re authenticating against.
HTTP 401 Unauthorized
The request has no valid authentication credentials — you need to log in or send a valid token.
error: cannot lock ref 'refs/remotes/origin/x': is at … but expected … / unable to update local ref
Git couldn’t update a reference — stale remote-tracking refs, case-only branch name clashes, or a leftover lock file.
fatal: No url found for submodule path 'x' in .gitmodules
A submodule entry exists in the index but its URL is missing from .gitmodules.
Error downloading object: x: Smudge error / This repository is over its data quota
Git LFS couldn’t download a large file — missing LFS install, auth problems, or the LFS bandwidth/storage quota is exhausted.
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