Why am I seeing 0xC0040008 in the TOP Server Event Log?

0xC0040008 means  'The item definition does not conform to the server syntax.'

This is an error code that can be sent by an OPC UA server when an AddItem request is sent by a client - In this case, TOP Server's OPC DA Client driver.

• Solution 1:
  • Verify that the tags address syntax matches the target server's syntax
• Solution 2:
  • Increase the amount of time before re-trying the lost server connection

• • • Channel Properties > Connection > Failed Connection Retry Interval (s)
  • Restart the TOP SErver runtime service to attempt re-connection