immich_server stops after changing UPLOAD_LOCATION in .env file

Yesterday I installed Immich on my Synology DS224+. Everything worked fine. After checking that Immich is up and running I changed the UPLOAD_LOCATION in the .env file from ./library to a shared folder where all my picture files are stored (/volume1/Bilder). After creating the Immich project again I get the error message "immich_server unexpectedly stopped ...". I have no idea what to do.