Failed to execute git checkout '9a3a499699a0d1c27330375087664dc2a9ce60a1' -- && git reset --hard '9a3a499699a0d1c27330375087664dc2a9ce60a1' -- fatal: reference is not a tree: 9a3a499699a0d1c27330375087664dc2a9ce60a1 It looks like the commit hash is not available in the repository, maybe the commit was removed from the branch? Run "composer update wporg/wporg-mu-plugins" to resolve this.