Tests that run setParameterOnAllHosts() like express.js will try to contact all nodes, including mongod s behind a router. So as expected, these tests are incompatible with any suite that does step up / step down (express.js is is tagged as such).

sharding_jscore_passthrough_with_config_transitions_and_add_remove_shard shuts down all mongod s and this means that tests that run setParameterOnAllHosts() can fail when run in this suite. For that reason we've already excluded many tests.

We need to prevent express.js and others that run setParameterOnAllHosts() from running in this suite. Either we can introduce a new tag (for example sets_param_on_all_hosts), use an existing tag and exclude these tests, or excluded them explicitly.