This document serves as a guide for users who wish to downgrade from an existing Mesos cluster to a previous version. This usually happens when rolling back from problematic upgrades. Mesos provides compatibility between any 1.x and 1.y versions of masters/agents as long as new features are not used. Since Mesos 1.8, we introduced a check for minimum capabilities on the master. If a backwards incompatible feature is used, a corresponding minimum capability entry will be persisted to the registry. If an old master (that does not possess the capability) tries to recover from the registry (e.g. when rolling back), an error message will be printed containing the missing capabilities. This document lists the detailed information regarding these minimum capabilities and remediation for downgrade errors.