Comment 4 for bug 1573075

It seems from RCA for this issue that it is caused by a change in logic of Nailgun and corresponding change to admin_network.json fixture. Parameter "gateway" was added to the fixture, and "use_gateway" validation was made more strict. Thus, the fixture from 6.0 creates admin network in DB, which is then restored into 8.0 Fuel Master DB 'as is'. But Nailgun code no longer supports the logic implied by the fixture. So it fails in the ways described above.

The proper solution to this bug would be to add data migration for admin_network metadata in module nailgun/util/migration.py and backport it to version 6.1.