Observability

Maintenance Schedules do not run after upgrading to SolarWinds Platform 2026.2

This article provides information about an issue in SolarWinds Platform 2026.2 and 2026.2.1 where recurring maintenance schedules (Mute Alerts or Unmanage) stop running after the SolarWinds Orion Module Engine service is restarted. When this occurs, scheduled maintenance windows no longer execute, and a System.FormatException is logged by ScheduledJobDAL in the Business Layer log. This is a confirmed regression compared to version 2026.1.

First published date

6/30/2026 10:46 PM

Last published date

7/1/2026 5:12 PM

Overview

After upgrading to SolarWinds Platform 2026.2 / 2026.2.1, maintenance schedules that are configured to mute alerts or unmanage entities during planned maintenance windows fail to run. The condition is triggered by a restart of the SolarWinds Orion Module Engine service, which routinely happens during upgrades, configuration changes, and standard troubleshooting.

 

Once the Module Engine restarts, the platform is unable to read the existing maintenance job definitions, so assigned schedules never fire. As a result, nodes and other entities that should be muted or unmanaged during a maintenance window remain fully managed, and alerts can continue to trigger during planned maintenance.

 

Typical symptoms reported by users:

  • Recurring maintenance schedules (Mute Alerts / Unmanage) no longer execute at their scheduled time.
  • Entities assigned to a schedule are not muted or unmanaged during the maintenance window.
  • The schedule appears correctly configured and assigned in the web console, but never runs.
  • Newly created schedules also fail to run after the next service restart.

 

The maintenance schedules are configured from the web console (for example, Settings > All Settings > Manage Maintenance Schedules), which continues to display the schedules as enabled even though they do not execute.

 

Sample log message

The following error is recorded in the Business Layer log (for example, C:\ProgramData\SolarWinds\Logs\Orion\Core.BusinessLayer.log) on the affected polling engine.

ERROR SolarWinds.Orion.Core.Common.DALs.ScheduledJobDAL - (null)  Caught exception while getting maintenance jobs: "Index (zero based) must be greater than or equal to zero and less than the size of the argument list." Exception details: System.FormatException: Index (zero based) must be greater than or equal to zero and less than the size of the argument list.
   at System.Text.StringBuilder.AppendFormatHelper(IFormatProvider provider, String format, ParamsArray args)
   at System.String.FormatHelper(IFormatProvider provider, String format, ParamsArray args)
   at System.String.Format(String format, Object arg0)
   at SolarWinds.Orion.Core.Common.DALs.ScheduledJobDAL.GetJobs(DataSet ds)
   at SolarWinds.Orion.Core.Common.DALs.ScheduledJobDAL.GetScheduledJobs()

Product section

Hybrid Cloud Observability

Cause

The issue is caused by a regression introduced in SolarWinds Platform 2026.2 in how existing maintenance schedules are loaded after the SolarWinds Orion Module Engine service restarts. When the service starts, it is unable to read the previously configured maintenance schedules, so the scheduler does not run any assigned schedules.

This behavior did not occur in version 2026.1 and is therefore classified as a regression.

Resolution

As of June 30, 2026, the fix implementation date has not yet been defined. Monitor this KB article and the SolarWinds Platform release notes for product fixes and enhancements.

Temporary workaround

After the SolarWinds Orion Module Engine service restarts, each affected maintenance schedule can be reloaded by making a small change to it. To do this:

  1. Go to Settings > All Settings > Manage Maintenance Schedules.
  2. Open an affected schedule and make a minor edit — for example, change the schedule description, or unassign and then re-assign an entity to the schedule.
  3. Save the schedule.
  4. Repeat for each affected schedule.

This forces the schedule to reload so it runs as expected. Note the following limitations:

  • This is a temporary workaround only. It must be repeated for each affected schedule after every restart of the SolarWinds Orion Module Engine service (for example, following upgrades, configuration changes, reboots, or troubleshooting).
  • Until each schedule is edited, it will not run, so alerts may continue to trigger and entities may remain managed during the intended maintenance window.
  • Newly created schedules are also affected and will not run after the next service restart until they are edited.