We deployed a webpart and when tried it to add it on the page, following error occurred:
Incompatible Web Part markup detected. Use *.dwp Web Part XML instead of *.webpart Web Part XML.
This error occurs when you have not inherited your class from “System.Web.UI.WebControls.WebParts.WebPart”. We have inheritated our class from “Microsoft.Office.Server.WebAnalytics.Reporting.WhatsPopularWebPart” class as we were customizing OOTB “WhatsPopularWebPart”. The resolution is to create your own “.dwp” file. Copy pate following XML, make appropriate changes and save it with “.dwp” extension.
One quick way is to open “.webpart” file and replace values.
Second step is to go to 14 hives or 12 hives [C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\FEATURES], found the feature folder. Delete “.webpart” file and paste “.dwp” file. Repeat the same process in the SharePoint installation. Go to Site Collection Settings-> Web parts (under Galleries). Delete “.webpart” file and upload “.dwp” file.