Nintex workflow web part error "The operation could not be completed because item was removed from the gallery"

Issue

For Sharepoint 2016 Environment , trying to add the Nintex workflow web parts  gives the following error :
"The operation could not be completed because item was removed from the gallery" 

 

Error Code

Error: "The operation could not be completed because item was removed from the gallery" 

Resolution

1. In the affected  site collection go to Site Settings -> Web Part Galleries – Remove the following web parts
   1. MyWorkflowTasks.webpart
   2. WorkflowChartViewer.webpart
   3. WorkflowReportViewer.webpart
   4. WorkflowsIStarted.webpart
2. Deactivate and re-activate the following Site collection features to add the web parts for the site collection
   1. Nintex Workflow 2016
   2. Nintex workflow 2016 Reporting Web Parts
   3. Nintex workflow 2016 Web Parts
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