OK. This is an error that will likely have you pulling your hair out (if you have hair :-)). Here is the scenario.
I have several website hosting accounts. One of those accounts is a Windows account that allows me to host multiple website (Deluxe Shared Hosting). I have MANY domains hosted on this account and the websites are a mixture of Asp.Net MVC, Asp.Net Webforms (yes...webforms still work :-)) and WordPress sites. I noticed an odd thing happening with the WordPress sites. From time to time, as I was working in the WordPress admin area, the sites would produce a 503 Service Unavailable error. Sometimes I would be editing a menu and click the Update button and would get the error. Sometimes I would make a change and try to visit the site and get the error. Sometimes I would make a theme edit and save and get the error. It happened at very random moments when some action was initiated on the server.
Initially, I thought it was the version of PHP being used for the shared hosting account, so I upgraded to version 5.4 (I was using 5.2). Nope! That did NOT solve the problem at all. OK. What next? I upgraded WordPress for one of the accounts and started hammering it. No resolution! I kept getting the intermittent 503 errors. OK. So now what? Next I started hammering my Asp.Net MVC websites to try to produce the error. Nope! Couldn't reproduce the 503 error on ANY of those sites. I did the same for the Webforms sites and could not reproduce the 503 error there either. So I realized the first fact about this error -
FACT #1 - The 503 Service Temporarily Unavailable error was ONLY happening on my Windows hosted accounts that had WordPress installed in their folders.
Interesting....
After realizing fact #1, I started to pay very close attention to what was happening when the error happened. I realized something. The error seemed to happen when some function had to be performed - ie. when something had to be saved. It didn't seem to happen on navigation only actions like going from page to page. However, I did notice that if the error happened when I was trying to perform an action in the admin panel, then I would also get the error on the website if I tried to bring that up at that moment. It was like the server was hanging on any server function other than serving pages and would get "stuck" for a few moments. It felt like the request for processing was happening too fast for the server to handle it so it would produce an error. Basically, the request for a function was coming in and being routed, but the underlying process could not move quickly enough to process it.
Since Google is my friend, I started researching the issue. I saw that many people had the 503 error on shared hosting accounts, but no one had a real solution - including the hosting companies! Now I'm no server expert, but this isn't rocket science either. How hard can it be for some of these hosting companies to examine their logs and come up with a solution? Based on what I read, it must be VERY hard for them to do that! Anywho.....I decided to keep researching.
I came across this from Microsoft -
https://support.microsoft.com/en-us/kb/2619402
That article gave me some great information. Since the Windows Deluxe shared hosting account allowed me to interact with IIS in a very limited way, I decided to see if I could tweak some settings in their to prevent, help, solve or stop the 503 errors from continuing to happen. By the way, my hosting account is using IIS 7.0. The IIS area provided by the website was very limited. However, it did allow me to switch from Integrated to Classic Pipeline mode. In integrated mode, all requests are handled in a unified pipeline. However, in classic mode, there are two pipelines. One is for native code applications and one is for managed code applications. You can look up the differences between native code and managed code, but essentially managed code needs a runtime to handle its execution. Native code executes on a particular processor and it takes it's instructions on how to run from the OS it is running on.
So, here is what I did. The IIS 7.0 pipeline was set to Integrated mode. I changed this to Classic. Then I recycled the App Pool. The combination of these two things stopped the 503 errors from happening. This should help you get your websites running if you are on a Windows shared hosting account with limited access to IIS. Do not forget to recycle the app pool.
I will keep you updated on how this "fix" holds. I have tested it quite a bit and haven't received a 503 error again....YET :-)!
If you are experiencing this issue on your shared Windows hosting account with WordPress, try this and let me know how it works for you.
Smooches,
Kila Morton
