Error while Saving a Workflow via SharePoint Designer Office 365

When you try to save custom workflow that's created in sharepoint designer, you may get the error message like "
Error while saving a workflow via sharepoint designer Office 365: Server-side activities have been updated. You need to restart SharePoint Designer to use the updated version of activities".
The resolution is simple.
  1. Close the SPD
  2. Delete the following folders where your SharePoint designer is installed

    <user profile>\appdata\roaming\microsoft\SharePoint Designer\ProxyAssemblyCache
    <user profile>\appdata\local\microsoft\websitecache\<sitename