A few days ago I just worked with the Content Editor Web Part (CEWB) when I received the following alerts after editing the HTML source of the web part:
"Cannot retrieve properties at this time” and “Cannot save your changes"
I found several references for this error on the web, but none of the proposed solutions (like AAM, trusted sites, etc.) solved my issue. After a short research I found the culprit: it was Fiddler, on of my favorite tools that intercepted the communication between SharePoint and my browser. Strange, that it did not helped when I turned off capturing of network traffic, only after shutting down the application disappeared the symptoms, and I was able to save the changes.
