Error: Cannot complete this action.

Error:  Cannot complete this action.
          Please try again.
          Troubleshoot issues with Windows SharePoint Services. 

      

What is the cause of this error? 

The short answer is that the page is trying to access something that doesn’t exist, or thinks does not exist.

Resolution:

1). To check which webpart is having the issue, open the site with SharePoint Designer  and double click on the page. The webpart which shows the ‘server error’ is the culprit one.

2). Right click on the webpart to visit its properties and to find its name.

3). Go to web part maintenance page by using http://xyz.com/sites/default.aspx?contents=1  and

4). Closed the offending web part.

If you have any queries/questions regarding the above mentioned information then please let me know. I would be more than happy to help you as well as resolves your issue. Thank you