Description

setFCV fails during the FCV 8.x ↔ 9.0 transition if there are index builds in progress, since it's incompatible with various upgrade requirements of FCV 9.0-gated features (SERVER-122468).

Now that 9.0 is last LTS, we can allow setFCV + index builds again to provide a more frictionless upgrade/downgrade experience for users.

Details

This requires removing or disabling the following two mechanisms:

• IndexBuildFCVStep (feasibility check)
• Registering index builds as "long running operations with a version context" which then causes setFCV to fail on the draining step.