Hi, I’m Hongli Lai, author of Passenger. We’ve just released version 5.0.4 which fixes more “this website is under heavy load” bugs. This is an important bug that can take sites down, so I all users who are on 5.0.1 and 5.0.2 to upgrade immediately.

I would like to apologize to you all that it has taken another release to fix this. I wrote the bulk of the new server code in Passenger 5. I wrote a web server from scratch in order to be able to reach the performance we need, but that also meant that a lot of new bugs (such as this one) have been introduced. The responsibility is mostly mine.

Version 5.0.2 also fixed a “this website is under heavy load” error, but that had an independent cause. 5.0.4 fixes two more cases. As far as we know, all critical issues have been fixed. We’ve fixed every critical issue reported to us so far. If you run into any more issues, please don’t hesitate to report them. We promised Passenger 5 is production ready, so we will make sure it is and we will give critical issues high priority.