Rob3r70 SharePoint Blog

Recently I have upgraded another client to SharePoint Subscription Edition from version 2013. As many others, this one as well had a lot of workflows running in old environment in the SharePoint 2010 workflow mode.

After the upgrade, workflows were not running with error “Failed to start”. Of course there were errors in the ULS logs like described in this article:

https://blog.stefan-gossner.com/2024/12/11/resolved-trending-issue-problems-with-workflows-after-applying-september-2024-cu-for-sharepoint-2016-2019-se/

But the issue was not actually resolved just by adding the entries to web.config and owstimer.exe.config. By the way, you can find owtimer.exe.config at path:

C:\Program Files\Common Files\microsoft shared\Web Server Extensions\16\BIN

So the ULS logs contained this entries

12/18/2025 19:14:11.17        w3wp.exe (0x2464)        0x3A34        SharePoint Foundation        Legacy Workflow Infrastructure        c42q0        High        Potentially malicious xoml node:

<ns0:RootWorkflowActivityWithData x:Class=”Microsoft.SharePoint.Workflow.ROOT” x:Name=”ROOT” xmlns=”http://schemas.microsoft.com/winfx/2006/xaml/workflow&#8221; xmlns:ns1=”clr-namespace:Microsoft.SharePoint.WorkflowActions.WithKey;Assembly=Microsoft.SharePoint.WorkflowActions, Version=15.0.0.0, Culture=neutral, PublicKeyToken=null” xmlns:x=”http://schemas.microsoft.com/winfx/2006/xaml&#8221; xmlns:ns0=”clr-namespace:Microsoft.SharePoint.WorkflowActions;Assembly=Microsoft.SharePoint.WorkflowActions, Version=15.0.0.0, Culture=neutral, PublicKeyToken=null”>   <ns0:RootWorkflowActivityWithData.WorkflowFields>    <ns0:WorkflowDataField Type=”System.String” Name=”__list” />    <ns0:WorkflowDataField

As you can see, the error log states that the issue is actually assembly version 15.0.0.0 and not 16.0.0.0. as the Stefan’s blog post states.

Whenever you upgrade to SharePoint SE and if you see the workflows “Failed to start”, add the following to your web.config and owstimer.exe.config and you should be fine.

<authorizedType Assembly="Microsoft.Office.Access.Server.Application, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" Namespace="Microsoft.Office.Access.Server.Macro.Runtime" TypeName="*" Authorized="True" />

<authorizedType Assembly="System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" Namespace="System.CodeDom" TypeName="*" Authorized="True" />

<authorizedType Assembly="Microsoft.SharePoint.WorkflowActions, Version=16.0.0.0, Culture=neutral, PublicKeyToken=null" Namespace="Microsoft.SharePoint.WorkflowActions.WithKey" TypeName="*" Authorized="True" />

<authorizedType Assembly="Microsoft.SharePoint.WorkflowActions, Version=16.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" Namespace="Microsoft.SharePoint.WorkflowActions.WithKey" TypeName="*" Authorized="True" />

<authorizedType Assembly="Microsoft.SharePoint.WorkflowActions, Version=15.0.0.0, Culture=neutral, PublicKeyToken=null" Namespace="Microsoft.SharePoint.WorkflowActions" TypeName="*" Authorized="True" />

<authorizedType Assembly="Microsoft.SharePoint.WorkflowActions, Version=15.0.0.0, Culture=neutral, PublicKeyToken=null" Namespace="Microsoft.SharePoint.WorkflowActions.WithKey" TypeName="*" Authorized="True" />

Hope this helps someone when upgrading SharePoint.