Wrong approve / reject page is shown in Nintex

In some cases you are presented the wrong page when trying to approve a task that was created by a Nintex workflow. The one you see is the original SharePoint page. While instead you should see the one with the option “Approve” and “Reject”

The problem here seems to be a mismatch in the connection between the taskform and a contenttype.

There is solution to this problem. You need to set the right taskform to be shown with the NintexWorkflowTask content type.
Use the nwadmin command line tool with the SetTaskForm operation

NWAdmin.exe -o SetTaskForm -siteUrl teamsiteurl -contentType contenttypename
  -taskformUrl taskformurl [-formType Edit|View|All] [-updatechildren Yes|No]

For example:
NWAdmin.exe -o SetTaskForm -siteUrl "http://portal/mynintexsite"
   -contentType "Nintex Workflow Task" -taskformUrl
   "_layouts/nintexworkflow/ApproveReject.aspx" -updatechildren Yes

Tip! This option also gives you the possibility to attach a custom approval page.

Note that when you installed Nintex Workflow 2007 in a different language you may need to translate the name of the contenttype.