Upgrade impossible from 3.1.0.11 to latest (3.1.

[Adeline-44]

I tried to upgrade via git pull => ok
Then go to myteampassurl.fr/install/upgrade => HTTP500
I go to the apache logs telling this problem : #4233
I fixed it, refrech my webpage => HTTP500
No I have this problem and fix it as describe : #4391

Refrech my webpage =>yeah, I got the instructions....but neither the NEXT button nor the START button work !!
No more error logs in apache...
What should I do ?

Thank you