SQL - Unknown error occurred

Hi. I’m trying to read another system mariadb, across the standard SQL integration modul, with these setup:
name: pi_cpu_temperature
database url:mysql+pymysql://ha:[email protected]/bme280_data?charset=utf8
column: cpu_temperature
select query: SELECT * FROM pi464 ORDER BY date_time DESC LIMIT 1
unit of measure: ˚C

And the answer in the window: Unknown error occurred.

The sql working, from another program, db acess ok.
Any idea?