Now, I have pbr 1.6, and this issue is occurred. So I installed pbr 1.8, but pbr 1.6 was installed by line 220 of /opt/stack/requirements/upper-constraints.txt
Now, I have pbr 1.6, and this issue is occurred. requirements/ upper-constrain ts.txt
So I installed pbr 1.8, but pbr 1.6 was installed by line 220 of /opt/stack/