Network Management

"Object reference not set to an instance of an object." message when accessing the Servers Tab in My Deployment page after upgrading to SolarWinds Platform 2025.2 or newer

You may experience an error when accessing the Servers Tab in My Deployment Page. The error points to "Object reference not set to an instance of an object." Unable to see the list of SolarWinds servers.

First published date

3/5/2026 7:24 PM

Last published date

3/5/2026 7:24 PM

Overview

After upgrading to SolarWinds Platform 2025.2 or later, you cannot see the list of SolarWinds Servers under the Servers Tab on the My Deployment Page.

Error:
  

"message": "An error has occurred.",
  "exceptionMessage": "Object reference not set to an instance of an object.",
  "exceptionType": "System.NullReferenceException",
  "stackTrace": " at SolarWinds.Orion.HA.WebApi.DataAccess.HAPoolRepository.FormatEngineVersion(String engineVersion)\r\n at SolarWinds.Orion.HA.WebApi.DataAccess.HAPoolRepository.GetListOfOrionServers(Boolean isAllServers)\r\n

 

 

 

Product section

Orion Platform

Cause

The issue is caused by a missing Engine entry in the Engines table for a Remote Collector.

During a normal agent-to-Remote Collector promotion, the system automatically creates an Engine of type RemoteCollector in the Engines table — along with corresponding EngineProperties entries that link the agent to the new Remote Collector Engine (via AgentId and AgentGuid). This allows the Remote Collector to function as a polling engine.

In this case, the Remote Collector's Engine entry was removed from the Engines table through one of the following actions:

  • Direct database deletion — the entry was manually removed from the Engines table at the database level.

  • Polling Engines page removal — the Remote Collector was deleted from Settings > All Settings > Polling Engines as a zero-node poller (the Delete unused polling engine option becomes available when no nodes are assigned to the Remote Collector).

However, the associated agent was not demoted or uninstalled — it still retains its Type = RemoteCollector (2) in the AgentManagement_Agents table. Because the agent continues to reference a Remote Collector Engine that no longer exists in the Engines table, the platform generates a missing EngineVersion query error on the Server page.

Resolution

Identify if there are agents that are currently promoted as Remote Collector:

  • Check the Agent Management Page and see if there are agents that are promoted to Remote Collector

 

  • Check if that Remote Collector Polling engine exists in the Polling Engines page.

  • If the Agent/Remote Collector is not seen on the Polling Engines page, you need to remove and re-add the agent to switch it back to Agent-only configuration

Note: removing the agent in Agent Management will also remove it as a monitored node, provided that the server where the agent is installed is itself monitored as a node. Proceed with Agent Deletion if you are not monitoring the node or if its historical data is not required.

    • If you want to promote the agent to a Remote Collector, you can check the Agent you want to promote and click More Actions, and "Promote Agent to Remote Collector" under the Agents tab in Agent Management page.

     

    Note: If neither of the scenarios above applies, capture a screenshot of the error along with the full error text from the Server page and raise a support ticket for further review.

     

    See also:

    “An error occurred. Nullable object must have a value." message when accessing the Servers and Pool tab after upgrading to SolarWinds Platform 2025.2

    "An error has occurred. An item with the same key has already been added." message when accessing the Servers and Pool tab after upgrading to SolarWinds Platform 2025.2