Too many errors in log

I have in log many these errors:
ERROR: Error unserializing state data
ERROR: Error executing alert script id 1. Return value -1.

Any advice? Thank you very much!

Could you post the output of

echo "SELECT hex(alerts_state) FROM clients WHERE alerts_state IS NOT NULL AND length(alerts_state)>0;" | sqlite3 /var/urbackup/backup_server.db

? Thanks!

64
64
04166C6173745F696D6167655F6661696C5F6E6F7469667903
04156C6173745F66696C655F6661696C5F6E6F7469667903
64
64
64
64
04156C6173745F66696C655F6661696C5F6E6F7469667903
04166C6173745F696D6167655F6661696C5F6E6F7469667903
64
64
64
04166C6173745F696D6167655F6661696C5F6E6F7469667903
04166C6173745F696D6167655F6661696C5F6E6F7469667903
04156C6173745F66696C655F6661696C5F6E6F7469667903
04166C6173745F696D6167655F6661696C5F6E6F7469667903
04166C6173745F696D6167655F6661696C5F6E6F7469667903
04156C6173745F66696C655F6661696C5F6E6F7469667903
04156C6173745F66696C655F6661696C5F6E6F7469667903
04166C6173745F696D6167655F6661696C5F6E6F7469667903
04166C6173745F696D6167655F6661696C5F6E6F7469667903

Seems to be an issue with storing null bytes. I wonder why it works for me? Are you using a separate sqlite? Or are you not using Linux etc.?

I’m using Debian Stretch. Package sqlite3 is installed.