Cannot create container for service webui


i am using Linux Mint and tried to install metasfresh.

After installation of docker and dockercompse i changed two lines in the yml.
ports - first port from 80:80 to 8080:80 and
-WEBAPI_URL=http://hostname:8080 where hostname is name of the host

When i try to start via dockercompose the following message appears

ERROR: for metasfresh:docker_webui_1 cannot create container for service webui: invalid mode: 8080

What can i do now?