Chris,
Dear Markus, the following error message occurs: DBMI-DBF driver error: Table 'messstationen' doesn't exist ERROR: Cannot open table
Since v.db.connect says there’s no table, try creating a table, then upload values into the table using v.to.db. After you’ve uploaded the values, you might need to use v.db.connect to set the connection to the table.
Or it may be that you have a table (if you’re using the dbf driver, the table will be in the dbf directory in the mapset folder), but the connection is lost. In that case, you can just use v.db.connect to reconnect the map to the table.
If the table exists, it will be in ///dbf/
Richard Chirgwin