arc land "Not possible to fast-forward, aborting."

Question

i am trying to land my arc patch. I am up-to-date with origin/master, my patch was reviewed and accepted. On teh phabricator site is says: Next Step arc land 'arcpatch-D37'. But if i use arc patch D37 and then arc land i run into problems.

It breaks at the pull:

Switched back to branch ←[1marcpatch-D37←[m.

[2014-04-29 14:06:50] EXCEPTION: (CommandException) Command failed with error #1
28!
COMMAND
git pull --ff-only --no-stat

STDOUT
(empty)

STDERR
fatal: Not possible to fast-forward, aborting.
at [D:\arcanist\libphutil\src\future\exec\ExecFuture.php:398]

I tried pulling first and had no problems/conflicts. No idea what to do/try next.

Answer 1

Try this:

1. git stash (make sure it's your only stash via git stash list)
2. git checkout master (switch to your master branch)
3. git branch -D arcpatch-D37 (delete the old branch)
4. git reset --hard origin/master (reset your current branch)
5. git pull (update the master branch)
6. arc patch D37 (create a fresh branch)
7. arc land (land it!)

Answer 2

Our team started working on a new feature branch and ran into this same error trying to land diffs. The fix for us was to ensure that the feature branch's upstream was set correctly.

1. git checkout <branch>
2. git branch --set-upstream-to=origin/<branch>
3. Go back to your patch or working branch and arc land