DatetimeFieldOverflow when inserting more than three decimals precision
Thanks to Akina, I found the problem. The error has been on client-side, because I used the following in the INSERT function:

INSERT INTO l12 VALUES (TO_TIMESTAMP('2019-05-23 12:16:50.954276', 'YYYY-MM-DD HH24:MI:SS.ms'))


which fails with the mentioned ERROR:  date/time field value out of range: "2019-05-23 12:16:50.954276"

Just remove that TO_TIMESTAMP function and be happy or use 'YYYY-MM-DD HH24:MI:SS.msus as the correct formating input.