Applications Systems

WPM Error: Unable to cast object of type 'System.DBNull' to type 'System.String'

This article provides brief information and steps to resolve the following error when adding transactions to a WPM Player: Unable to cast object of type 'System.DBNull' to type 'System.String'

First published date

10/22/2018 9:45 AM

Last published date

1/7/2022 6:16 PM

Overview

This article discusses brief information and needed steps to correct the following error message when adding transactions to a WPM Player:

Unable to cast object of type 'System.DBNull' to type 'System.String'

Product section

Web Performance Monitor

Cause

The issue is caused by an Orion Migration to a new Server with a new Hostname/IP Address.

This causes a new entry to be created in the Engines table but it doesn't update the WPM Agents table with the new Engine ID.

Resolution

  1. Open Database Manager.
  2. Right-click the Orion Database, and then select New Query.
  3. Paste the following in: 
    SELECT * FROM Engines
Scripts are not supported under any SolarWinds support program or service. Scripts are provided AS IS without warranty of any kind. SolarWinds further disclaims all warranties including, without limitation, any implied warranties of merchantability or of fitness for a particular purpose. The risk arising out of the use or performance of the scripts and documentation stays with you. In no event shall SolarWinds or anyone else involved in the creation, production, or delivery of the scripts be liable for any damages whatsoever (including, without limitation, damages for loss of business profits, business interruption, loss of business information, or other pecuniary loss) arising out of the use of or inability to use the scripts or documentation.
  1. Take note of the [EngineID] of your Primary Polling Engine.
  2. Now run the following query (Please note this will update the WPM Agents to all talk to the Primary). 
    UPDATE [SEUM_Agents] SET [PollingEngineID] = X --Where X is your primary ID

     

  3. If you have WPM Player which also talks to Additional Polling Engines then do the following:

    SELECT * FROM [SEUM_Agents]

  4. Enable Table Editing.

  5. Change the [PollingEngineID] of the Players who need to communicate with Additional Polling Engines as opposed to Main Polling Engine.