SharePoint security fixes released with August 2026 PU and offered through Microsoft Update

16 Comments

1. 

   Andre
   On 13. August 2026 Permalink

   Hello Stefan,

   We have applied the August 2026 CU in SharePoint SE and SharePoint 2016 in test environment. Previously, we had issues with the workflow failing to start/failing to run and we were fixing them by adding the required assemblies on the web.config files. We have some questions:

   Do we need to remove the rewrite rule (which was the provided workaround on the workflow status URL) in the web.config files from the WFE server, or can it be retained?
   We noticed that below assembly has been gone in the web.config files after applying the August 2026 CU. Should we add it again?

   “”

   Thank you very much!

   Reply
   1. 

      Andre
      On 13. August 2026 Permalink

      For the second question, here’s the assembly/authorizedType :

      authorizedType Assembly=”System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089″ Namespace=”System.CodeDom” TypeName=”*” Authorized=”True”

      Reply
      1. 

         Stefan Goßner
         On 13. August 2026 Permalink

         Afaik this is still required.

         Reply
   2. 

      Stefan Goßner
      On 13. August 2026 Permalink

      Hi Andre,

      You can remove rewrite rule if August CU is installed.

      Cheers,
      Stefan

      Reply
2. 

   Vicki
   On 14. August 2026 Permalink

   After applying the update to our on-premises farm, the Document ID service has issues.

   This is empty
   $farm.GetGenericAllowedListValues(„AllowedDLCAssemblies“)
   across all environments.

   Reply
3. 

   Charles
   On 15. August 2026 Permalink

   All the workflows now have failed to start message since august 2026 CU on SharePoint SE

   Reply
   1. 

      Charles
      On 15. August 2026 Permalink

      I forgot to mention I have this message when I try to publish them : Errors were found when compiling the workflow. The workflow files we saves but cannot be run. Unexpected error on server associating the workflow

      Reply
4. 

   Tong Chang
   On 18. August 2026 Permalink

   The workflow still failed on start. It did not fix the default workflow issue.

   Reply
   1. 

      Anthony
      On 18. August 2026 Permalink

      Same problem here…. I applied the july update 2 weeks ago and did the fix from Stefan and it worked great. Since the august update, failed on start…

      Reply
   2. 

      Matthias
      On 18. August 2026 Permalink

      Looks like some could not wait until September CU. The Workflow Engines have been disabled with this Update in my Environments and i must enable them again.

      Reply
5. 

   Ax
   On 24. August 2026 Permalink

   I amd still getting “Unauthorized” from SPWFM workflows after installing the August 2026 SharePoint CU

   Reply
   1. 

      Stefan Goßner
      On 25. August 2026 Permalink

      Hi Ax,

      I would recommend to open a ticket with Microsoft support to get this analyzed in more detail.

      Cheers,
      Stefan

      Reply
6. 

   Fernando
   On 1. September 2026 Permalink

   Hello! Thanks for your help. May I ask why this update exists? SharePoint 2016 reached its end of life on July, why did we get a new update? Can we expect more updates on the near future?

   Reply
   1. 

      Stefan Goßner
      On 1. September 2026 Permalink

      It contains fixes for security issues which were identified before end of life.

      No further updates are planned.

      Reply
7. 

   Siva
   On 2. September 2026 Permalink

   Search stopped working through out all our 2016 and 2019 farms. Any suggestions on this

   Reply
   1. 

      Stefan Goßner
      On 3. September 2026 Permalink

      Hi Siva,

      Please share more details.
      Is it search or crawl?
      What errors do you get in the UI and in ULS?

      Cheers,
      Stefan

      Reply