Im trying to push to github with sourcetree but get the following error:
git -c diff.mnemonicprefix=false -c core.quotepath=false push -v --tags origin
I just solved this problem by using an access token. I use macbook, all answers above didn't work for me. Go to your github account, click your profile image on right top corner, then click:
Settings -> Developer settings -> Personal access tokens -> Generate new token
Paste this token into sourcetree popup window, required password area, instead of typing your account password. Github uses two step verification, so you need to use a token rather than account password. Good luck! Let me know if this works for you.