Use your browser's developer tools (commonly launched with F12 key), enable Network tracing and don't clear history "on navigate". There should be a call to the Nintex Workflow Web service from the page. Please have a look at the response and find error details there. If that's not sufficient, head over to admins and ask them to parse ULS logs for errors in the vicinity of the moment where you tried to publish. Remind them of the Merge-SPLogFile cmdlet.
I traced the SharePoint logs and found the following :
Workflow dll failed to compile because it exceeded UserDefinedWorkflowMaximumComplexity of 7000
(http://XYZABC/_vti_bin/NintexWorkflow/Workflow.asmx): Nintex.Workflow.NWSavingWorkflowException: Failed to publish workflow: Error in the application. (Build:3190), Error saving from workflow export file.: Nintex.Workflow.NWSavingWorkflowException: Failed to publish workflow: Error in the application.
I increased the UserDefinedWorkflowMaximumComplexity using the following PowerShell :
[System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SharePoint") $new_limit = 50000; $webapp = [Microsoft.SharePoint.Administration.SPWebApplication]::Lookup('webApplicationURL) $webapp.UserDefinedWorkflowMaximumComplexity = $new_limit $webapp.Update()
it is fixed and I could publish my workflows successfully.