"Configure Action" results in exception after migration

Hello,

We have the following problem in a farm installation of sharepoint 2013, which we cant seem to get rid of:

After migrating a SharePoint 2010 Installation to SharePoint 2013, the farm consists of a Web Front End Server, an Application Server and a Database Server.

The WebApps in question run in SP 2013 with 2010 Display Mode.

All WebApps except Central Administration run on the Web Front End.

After migrating, the pre-existing Nintex Workflows work just the same, but when editing certain actions in new or existing workflows in some web applications, an error occurs.

These web applications have to following alternate access mappings:

 Internal URL

·        Creating a new List Workflow

·        Adding the “Set Item Permissions”-Action works just fine

Editing the Action on the other hand results in an exception, and behind the correlation id:

Application error when access /_layouts/NintexWorkflow/SetItemPermissions.aspx, Error=Could not load type 'Nintex.Workflow.ApplicationPagesV14.Activities.SetItemPermissions' from assembly 'Nintex.Workflow.ApplicationPages, Version=1.0.0.0, Culture=neutral, PublicKeyToken=913f6bae0ca5ae12'.
at System.Reflection.RuntimeAssembly.GetType(RuntimeAssembly assembly, String name, Boolean throwOnError, Boolean ignoreCase, ObjectHandleOnStack type) 
at System.Reflection.RuntimeAssembly.GetType(String name, Boolean throwOnError, Boolean ignoreCase) 
at System.Web.UI.TemplateParser.GetType(String typeName, Boolean ignoreCase, Boolean throwOnError) 
at System.Web.UI.TemplateParser.ProcessInheritsAttribute(String baseTypeName, String codeFileBaseTypeName, String src, Assembly assembly) 
at System.Web.UI.TemplateParser.PostProcessMainDirectiveAttributes(IDictionary parseData)

System.TypeLoadException: Could not load type 'Nintex.Workflow.ApplicationPagesV14.Activities.SetItemPermissions' from assembly 'Nintex.Workflow.ApplicationPages, Version=1.0.0.0, Culture=neutral, PublicKeyToken=913f6bae0ca5ae12'.
at System.Reflection.RuntimeAssembly.GetType(RuntimeAssembly assembly, String name, Boolean throwOnError, Boolean ignoreCase, ObjectHandleOnStack type) 
at System.Reflection.RuntimeAssembly.GetType(String name, Boolean throwOnError, Boolean ignoreCase) 
at System.Web.UI.TemplateParser.GetType(String typeName, Boolean ignoreCase, Boolean throwOnError) 
at System.Web.UI.TemplateParser.ProcessInheritsAttribute(String baseTypeName, String codeFileBaseTypeName, String src, Assembly assembly) 
at System.Web.UI.TemplateParser.PostProcessMainDirectiveAttributes(IDictionary parseData)

Getting Error Message for Exception System.Web.HttpParseException (0x80004005): Could not load type 'Nintex.Workflow.ApplicationPagesV14.Activities.SetItemPermissions' from assembly 'Nintex.Workflow.ApplicationPages, Version=1.0.0.0, Culture=neutral, PublicKeyToken=913f6bae0ca5ae12'. ---> System.Web.HttpParseException (0x80004005): Could not load type 'Nintex.Workflow.ApplicationPagesV14.Activities.SetItemPermissions' from assembly 'Nintex.Workflow.ApplicationPages, Version=1.0.0.0, Culture=neutral, PublicKeyToken=913f6bae0ca5ae12'. ---> System.TypeLoadException: Could not load type 'Nintex.Workflow.ApplicationPagesV14.Activities.SetItemPermissions' from assembly 'Nintex.Workflow.ApplicationPages, Version=1.0.0.0, Culture=neutral, PublicKeyToken=913f6bae0ca5ae12'. 
at System.Reflection.RuntimeAssembly.GetType(RuntimeAssembly assembly, String name, Boolean throwOnError, Boolean ignoreCase, ObjectHandleOnStack type) 
at System.Reflection.RuntimeAssembly.GetType(String name, Boolean throwOnError, Boolean ignoreCase) 
at System.Web.UI.TemplateParser.GetType(String typeName, Boolean ignoreCase, Boolean throwOnError) 
at System.Web.UI.TemplateParser.ProcessInheritsAttribute(String baseTypeName, String codeFileBaseTypeName, String src, Assembly assembly) 
at System.Web.UI.TemplateParser.PostProcessMainDirectiveAttributes(IDictionary parseData) 
at System.Web.UI.TemplateParser.ProcessException(Exception ex) 
at System.Web.UI.TemplateParser.ParseStringInternal(String text, Encoding fileEncoding) 
at System.Web.UI.TemplateParser.ParseString(String text, VirtualPath virtualPath, Encoding fileEncoding) 
at System.Web.UI.TemplateParser.ParseString(String text, VirtualPath virtualPath, Encoding fileEncoding) 
at System.Web.UI.TemplateParser.ParseFile(String physicalPath, VirtualPath virtualPath) 
at System.Web.UI.TemplateParser.Parse() 
at System.Web.Compilation.BaseTemplateBuildProvider.get_CodeCompilerType() 
at System.Web.Compilation.BuildProvider.GetCompilerTypeFromBuildProvider(BuildProvider buildProvider) 
at System.Web.Compilation.BuildProvidersCompiler.ProcessBuildProviders() 
at System.Web.Compilation.BuildProvidersCompiler.PerformBuild() 
at System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath) 
at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate) 
at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate) 
at System.Web.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean throwIfNotFound) 
at System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext context, Boolean allowCrossApp) 
at System.Web.UI.PageHandlerFactory.GetHandlerHelper(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath) 
at System.Web.HttpApplication.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() 
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
 

Normal 0 21 false false false DE-AT X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:8.0pt; mso-para-margin-left:0cm; line-height:107%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-fareast-language:EN-US;} table.MsoTableGrid {mso-style-name:"Table Grid"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-priority:39; mso-style-unhide:no; border:solid windowtext 1.0pt; mso-border-alt:solid windowtext .5pt; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-border-insideh:.5pt solid windowtext; mso-border-insidev:.5pt solid windowtext; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-fareast-language:EN-US;}

We tried accessing the workflow using the internal address (http://wfeservername:port) as well as the external address (https://portalurl), both yield the same exception.

On the same server, there is also a Web Application which runs in 2013 mode, where this problem does not occur. It has the following alternate access mapping:

We also tried removing the action from the allowed actions and adding it back again, as well as enabling/disabling Nintex Workflow 2013, but nothing seems to work. 

Any help regarding this problem would be very much appreciated!

Thanks, Martin