WCCOAnextgenarch - IMPL/SEVERE - Database error, Error while writing values, database response: [shard 825] invalid character '\x00'

Enclosed you'll find the explanation for a log-message which can occur during runtime when using Influx as NGA database. The messages are written to the PVSS_II.log-file.

WCCOAnextgenarch(118), 2024.07.02 15:32:18.000, IMPL, SEVERE,     69, Database error, Error while writing values, database response: [shard 825] invalid character '\x00' looking for beginning of value (from System1:_NGA_B_InfluxDB)

Log-message with symbolic names:

WCCOAnextgenarch(118), <TIMESTAMP>, IMPL, SEVERE,     69, Database error, Error while writing values, database response: [shard <shard number>] invalid character '\x00' looking for beginning of value (from <NGA Influx backend name>)

This log-message describes that the NGA Manager cannot write data into a segment in the Influx database. The error can occur when the Influx database got damaged before, e.g. by a power cut at the machine.
The problem leads possibly to the effect that no data is written and data is buffered.

To correct the database you can execute the following steps. Please take into account that data is lost by deletion of shards from the database.

-- Open a command shell
-- Navigate to the bin folder of WinCC OA installation or the folder where Influx is installed
-- Call the command to connect to the database, the default name for the databae is "winccoa"
influx -database <database name>
-- Do the authentication by calling "auth"
-- Define the username and password
-- Delete the shard with the following command, the shard number is shown at the log message
drop shard <shard number>
If several shards are affected, delete all of them.
-- Close the connection to the Influx database with the command "quit"

If buffer files have been existing when the log message occured, please check if they are processed after deleting the shard.