Failed to load the plugin because: Could not initialize the plugin sandbox. Deadline 10.2.1.1

Hi to all, we have Render Farm with 20 nodes working properly with Deadline 10.2.1.1, We execute Maya 2025 Redshift renders, Maya 2024 Arnold Renders, Nuke Jobs and commandline jobs.

We install a new node and add to the Render Farm:

  • Windows 11 Pro updated to 25H2
  • Deadline client 10.2.1.1
  • Autodesk Maya 2025.2 and 2024.3 installed

But when we try to use the new job we get the same error:


2025-10-28 10:38:15:  0: Got task!
2025-10-28 10:38:15:  0: Render Thread - Render State transition from = 'ReceivedTask' to = 'Other'
2025-10-28 10:38:15:  0: Plugin will be reloaded because a new job has been loaded.
2025-10-28 10:38:15:  0: Loading Job's Plugin timeout is Disabled
2025-10-28 10:38:15:  0: SandboxedPlugin: Render Job As User disabled, running as current user 'a.render01'
2025-10-28 10:38:15:  ERROR: Encountered the following error while initializing the Plugin Sandbox: 'Object reference not set to an instance of an object.'.
2025-10-28 10:38:15:   Cannot render the current job [ID:"68f8e8bc604765854b93af2a" / Name:"XXXXXXXXXXXXXXXXXXXXX"]. Contact Thinkbox Support for more information.
2025-10-28 10:38:15:  ERROR: 0: An exception occurred: Failed to load the plugin because: Could not initialize the plugin sandbox (Deadline.Plugins.PluginException) (Deadline.Plugins.RenderPluginException)
2025-10-28 10:38:16:  0: Render Thread - Render State transition from = 'Other' to = 'WaitingForTask'
2025-10-28 10:38:17:  Scheduler Thread - Render Thread 0 threw a major error: 
2025-10-28 10:38:17:  >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
2025-10-28 10:38:17:  Exception Details
2025-10-28 10:38:17:  RenderPluginException -- Failed to load the plugin because: Could not initialize the plugin sandbox (Deadline.Plugins.PluginException)
2025-10-28 10:38:17:  RenderPluginException.Cause: PluginLoadError (0)
2025-10-28 10:38:17:  RenderPluginException.Level: Major (1)
2025-10-28 10:38:17:  RenderPluginException.HasSlaveLog: True
2025-10-28 10:38:17:  RenderPluginException.SlaveLogFileName: C:\ProgramData\Thinkbox\Deadline10\logs\deadlineslave_renderthread_0-BL-RENDER-03-0000.log
2025-10-28 10:38:17:  Exception.TargetSite: Boolean e(System.String, Deadline.Jobs.Job, System.Threading.CancellationToken)
2025-10-28 10:38:17:  Exception.Data: ( )
2025-10-28 10:38:17:  Exception.Source: deadline
2025-10-28 10:38:17:  Exception.HResult: -2146233088
2025-10-28 10:38:17:    Exception.StackTrace: 
2025-10-28 10:38:17:     at Deadline.Slaves.SlaveRenderThread.e(String ajx, Job ajy, CancellationToken ajz)
2025-10-28 10:38:17:     at Deadline.Slaves.SlaveRenderThread.b(TaskLogWriter ajt, CancellationToken aju)

Any idea why this new installation is not working well??

Thanks!

New extra info from logs:

WARNING: Encountered the following error while initializing the Event Sandbox: 'Object reference not set to an instance of an object.'.
2025-10-28 12:13:26:  Falling back to embedded Event Manager -- this may result in stale Python environments being used.