The most common error, when the folder tree on the left stays empty is that something blocks the internal API. PaperOffice uses ports 8890, 8891, and 8892 for internal API access. please check if something on your PC is blocking these ports or if another application is already using this port. You can simpy check this by starting PaperOffice until you see the surface with the missing folder tree and then open your browser and access this page: http://localhost:8890/ajax.php?cmd=ping If you see something like this: „{ POcrypt_response: "13b33a6df5b1913bad4df5acc06f71f7:c928956b5b306c7d33e885aad9ab8ae1915e8471:jHCpp7AsD6UYeVrNDM4Rb7fUVcyRE7Fg92DzBUyTetcjbBkgtds7aFtnSYMweXr", POcrypt_keytoken: "g7t3y2ni2o9gvbd6" }“ then everything is fine and the API is not blocked. If you have an antivirus software installed, it may also be the cause of the antivirus vendor blocking the application. Check internally whether PaperOffice components are blocked by this, add PaperOffice to the exclusion list, or contact your antivirus vendor if necessary to resolve this issue.