Failed to execute git checkout '0fb29a472611c584a13632c7167666666446ab7c' -- && git reset --hard '0fb29a472611c584a13632c7167666666446ab7c' -- fatal: unable to read tree (0fb29a472611c584a13632c7167666666446ab7c) It looks like the commit hash is not available in the repository, maybe the commit was removed from the branch? Run "composer update silverstripe/admin" to resolve this.