Problem storing data in database

[angelo-veltens at web.de]

Hello together, 

I am trying to connect gnucash to a postgres database, but cannot get it running. When trying to save, following error pops up in the GUI: 

Der Server unter der URL »postgres://gnucash@localhost/gnucash« stiess auf einen Fehler oder benutzte falsche oder fehlerhafte Daten. 

Connection via JDBC using a database tool works fine! 

Following errors occur in the gnucash.trace file: 

* 18:56:22  WARN <gnc.backend.dbi> [gnc_dbi_postgres_session_begin()] Databse already exists, Might clobber it. 
* 18:56:24  CRIT <gnc.backend.dbi> conn_table_operation: assertion 'table_name_list != NULL' failed 
* 18:56:24  CRIT <gnc.backend.dbi> conn_table_operation: assertion 'table_name_list != NULL' failed 
* 18:56:25  WARN <gnc.backend.dbi> [gnc_dbi_unlock()] No lock table in database, so not unlocking it. 

My setup: 
 - gnucash 2.6.12 on fedora linux 
 - postgresql 9.6 with an empty schema named "gnucash" and a user "gnucash" that has all permissions granted to it 
 - libdbi 0.9.0 
 - libdbi-dbd-pgsql 0.9.0 

What's happening here? 

Thanks in advance! 

Best regards, 
Angelo