raise util.CommandError('Only a single head is supported. The '
alembic.util.CommandError: Only a single head is supported. The script directory has multiple heads (due to branching), which must be resolved by manually editing the revision files to form a linear sequence. Run alembic branches to see the pergence(s).

• flask部落格部署到heroku時，在pus到heroku後運行時報錯誤。貌似是git 分支的問題？不知道怎麼解決。

• 我找到了一段解決方法： this happens when you go back to a revision that is not the last and then create a new migration. Now you have two branches, which Alembic cannot handle. Look at howm , whichfiles the mare together through migration ids, you need to create a linear chain to collapse the branches.

• 看的不太懂。不知道how?

• 十分感謝。