From the librenms.log
Error discovering sensors module for 10.8.0.201. PDOException: SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'sensor_oid' cannot be null in /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Connection.php:587
Stack trace:
#0 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Connection.php(587): PDOStatement->execute()
#1 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Connection.php(816): Illuminate\Database\Connection->Illuminate\Database\{closure}()
#2 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Connection.php(783): Illuminate\Database\Connection->runQueryCallback()
#3 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Connection.php(576): Illuminate\Database\Connection->run()
#4 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Connection.php(540): Illuminate\Database\Connection->statement()
#5 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Query/Processors/Processor.php(32): Illuminate\Database\Connection->insert()
#6 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Query/Builder.php(3507): Illuminate\Database\Query\Processors\Processor->processInsertGetId()
#7 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Builder.php(1982): Illuminate\Database\Query\Builder->insertGetId()
#8 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Model.php(1334): Illuminate\Database\Eloquent\Builder->__call()
#9 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Model.php(1299): Illuminate\Database\Eloquent\Model->insertAndSetId()
#10 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Model.php(1138): Illuminate\Database\Eloquent\Model->performInsert()
#11 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Relations/HasOneOrMany.php(287): Illuminate\Database\Eloquent\Model->save()
#12 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Relations/HasOneOrMany.php(312): Illuminate\Database\Eloquent\Relations\HasOneOrMany->save()
#13 /opt/librenms/LibreNMS/DB/SyncsModels.php(74): Illuminate\Database\Eloquent\Relations\HasOneOrMany->saveMany()
#14 /opt/librenms/LibreNMS/DB/SyncsModels.php(95): App\Discovery\Sensor->syncModels()
#15 /opt/librenms/app/Discovery/Sensor.php(97): App\Discovery\Sensor->syncModelsByGroup()
#16 /opt/librenms/includes/discovery/functions.inc.php(804): App\Discovery\Sensor->sync()
#17 /opt/librenms/includes/discovery/sensors.inc.php(85): sensors()
#18 /opt/librenms/includes/discovery/functions.inc.php(170): include('...')
#19 /opt/librenms/discovery.php(108): discover_device()
#20 {main}
Next Illuminate\Database\QueryException: SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'sensor_oid' cannot be null (Connection: mysql, SQL: insert into `sensors` (`poller_type`, `sensor_class`, `device_id`, `sensor_oid`, `sensor_index`, `sensor_type`, `sensor_descr`, `sensor_divisor`, `sensor_multiplier`, `sensor_limit`, `sensor_limit_warn`, `sensor_limit_low`, `sensor_limit_low_warn`, `sensor_current`, `entPhysicalIndex`, `entPhysicalIndex_measured`, `user_func`, `group`, `rrd_type`) values (snmp, humidity, 3127, ?, sensor6name, serverscheck, Humidity1, 1, 1, 70, ?, 30, ?, 39.68, ?, ?, ?, ?, GAUGE)) in /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Connection.php:829
Stack trace:
#0 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Connection.php(783): Illuminate\Database\Connection->runQueryCallback()
#1 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Connection.php(576): Illuminate\Database\Connection->run()
#2 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Connection.php(540): Illuminate\Database\Connection->statement()
#3 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Query/Processors/Processor.php(32): Illuminate\Database\Connection->insert()
#4 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Query/Builder.php(3507): Illuminate\Database\Query\Processors\Processor->processInsertGetId()
#5 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Builder.php(1982): Illuminate\Database\Query\Builder->insertGetId()
#6 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Model.php(1334): Illuminate\Database\Eloquent\Builder->__call()
#7 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Model.php(1299): Illuminate\Database\Eloquent\Model->insertAndSetId()
#8 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Model.php(1138): Illuminate\Database\Eloquent\Model->performInsert()
#9 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Relations/HasOneOrMany.php(287): Illuminate\Database\Eloquent\Model->save()
#10 /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Relations/HasOneOrMany.php(312): Illuminate\Database\Eloquent\Relations\HasOneOrMany->save()
#11 /opt/librenms/LibreNMS/DB/SyncsModels.php(74): Illuminate\Database\Eloquent\Relations\HasOneOrMany->saveMany()
#12 /opt/librenms/LibreNMS/DB/SyncsModels.php(95): App\Discovery\Sensor->syncModels()
#13 /opt/librenms/app/Discovery/Sensor.php(97): App\Discovery\Sensor->syncModelsByGroup()
#14 /opt/librenms/includes/discovery/functions.inc.php(804): App\Discovery\Sensor->sync()
#15 /opt/librenms/includes/discovery/sensors.inc.php(85): sensors()
#16 /opt/librenms/includes/discovery/functions.inc.php(170): include('...')
#17 /opt/librenms/discovery.php(108): discover_device()
#18 {main}
SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'sensor_oid' cannot be null (Connection: mysql, SQL: insert into `sensors` (`poller_type`, `sensor_class`, `device_id`, `sensor_oid`, `sensor_index`, `sensor_type`, `sensor_descr`, `sensor_divisor`, `sensor_multiplier`, `sensor_limit`, `sensor_limit_warn`, `sensor_limit_low`, `sensor_limit_low_warn`, `sensor_current`, `entPhysicalIndex`, `entPhysicalIndex_measured`, `user_func`, `group`, `rrd_type`) values (snmp, humidity, 3127, ?, sensor6name, serverscheck, Humidity1, 1, 1, 70, ?, 30, ?, 39.68, ?, ?, ?, ?, GAUGE)) {"exception":"[object] (Illuminate\\Database\\QueryException(code: 23000): SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'sensor_oid' cannot be null (Connection: mysql, SQL: insert into `sensors` (`poller_type`, `sensor_class`, `device_id`, `sensor_oid`, `sensor_index`, `sensor_type`, `sensor_descr`, `sensor_divisor`, `sensor_multiplier`, `sensor_limit`, `sensor_limit_warn`, `sensor_limit_low`, `sensor_limit_low_warn`, `sensor_current`, `entPhysicalIndex`, `entPhysicalIndex_measured`, `user_func`, `group`, `rrd_type`) values (snmp, humidity, 3127, ?, sensor6name, serverscheck, Humidity1, 1, 1, 70, ?, 30, ?, 39.68, ?, ?, ?, ?, GAUGE)) at /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Connection.php:829)
[previous exception] [object] (PDOException(code: 23000): SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'sensor_oid' cannot be null at /opt/librenms/vendor/laravel/framework/src/Illuminate/Database/Connection.php:587)"}