The API is returning the following error message when I request the revision history for locked posts. Example URL: http://api.stackoverflow.com/1.1/revisions/194812 { "error": { "code": 500, "message": "A generic error has occurred on the server; developers have been notified." } } I've tried this through the [API Console][1], directly in my browser, and in code (with and without an API key). Here's a sample from some of the top posts on Stack Overflow. Locked: - [List of freely available programming books][2] - [What is the single most influential book every programmer should read?][3] - [Hidden Features of C#?][4] - [Strangest language feature \[closed\]][5] - [What are the lesser known but cool data structures?][6] Not locked: - [Hidden features of Python][7] - [Flash CS4 refuses to let go][8] - [What IDE to use for Python?][9] - [What is the name of this operator: “-->”?][10] - [RegEx match open tags except XHTML self-contained tags][11] - [The Definitive C++ Book Guide and List][12] - [Most useful free .NET libraries? \[closed\]][13] All of the **locked** questions give the error message above, while all of the questions that are not locked return a normal revision history. Other question states like **closed** and **protected** seem to have no effect. Finally, I did one last test. I was able to successfully fetch the revision history of [Twitter image encoding challenge \[closed\]][14] before it was locked (note that is was protected and closed prior to testing) but after it was locked I got [the same error message][15]. [1]: http://api.stackoverflow.com/1.1/usage/methods/revisions [2]: http://api.stackoverflow.com/1.1/revisions/194812 [3]: http://api.stackoverflow.com/1.1/revisions/1711 [4]: http://api.stackoverflow.com/1.1/revisions/9033 [5]: http://api.stackoverflow.com/1.1/revisions/1995113 [6]: http://api.stackoverflow.com/1.1/revisions/500607 [7]: http://api.stackoverflow.com/1.1/revisions/101268 [8]: http://api.stackoverflow.com/1.1/revisions/2193953 [9]: http://api.stackoverflow.com/1.1/revisions/81584 [10]: http://api.stackoverflow.com/1.1/revisions/1642028 [11]: http://api.stackoverflow.com/1.1/revisions/1732348 [12]: http://api.stackoverflow.com/1.1/revisions/388242 [13]: http://api.stackoverflow.com/1.1/revisions/662956 [14]: http://stackoverflow.com/questions/891643/twitter-image-encoding-challenge [15]: http://api.stackoverflow.com/1.1/revisions/891643