SharePoint Rest API call returns 500.50 URL rewrite error

The Story

Hey all another SharePoint Story here!

So my dev was working on another SharePoint site app. We did everything like before, and now he was getting a URL rewrite error. I wasn’t sure why this was happening, and since he generally had more experience troubleshooting  these types of issues I sort of let him handle it for a while.

Well after a while he still couldn’t figure it out, and funny thing happened, we learned some interesting things and got bit by erroneous error messages in the end. So the first thing he tried was to give his re-write rules some new variable names. Which didn’t help and the same error was returned.

After a little while I had forgot to set the Service Principal Names (SPNs) for the new web applications we created for the new SharePoint sites. I was certain this was it, but we kept getting a URL rewrite error! (This turns out was actually the initial reason for the error, yeah it really was cause it turns out…)

I showed by dev this post by Scott on the same error. Now the reason we were getting the same URL rewrite error was cause when he changed the variable names in his re-write rule he didn’t change their associated server variables as mentioned in Scotts blog.

The Answer

The only reason we got the error both times was simply a coincidence. So it turns out:

1) If you forget to set the SPN when you Web App is set for Kerberos, and your hosting app server is on another server. You will get a re-write error if you have everything else in place.

2) If you change variables in your re-write rule and forget to set the associated system variables with it.

Both will result in a 500.50 URL rewrite error… who would of figured…