You have not concluded your merge (MERGE_HEAD exists)

Problems with Using SourceTree Merge branches:

You have not concluded your merge (MERGE_HEAD exists).
Please, commit your changes before you can merge.

Then click Termianl on SourceTree and an error occurs:

The error may be caused by code that you pulled down before not merging automatically.
There are two solutions:
1. Keep your local changes

git merge --abort

git reset --merge

Be sure to commit the local merge after merging
Then get the online warehouse

git pull

2. Down the code version, discard local modifications
This is not recommended, but if you have small local changes, or if you have a backup copy of your own, you can overwrite it locally directly with the latest version on your line

git fetch --all

git reset --hard origin/master

git fetch

Of course, the dumbest option is to clone a piece of code and discard the working directory, which is clumsy but equally effective.

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