Getting random IIS 403 errors on static files and how to fix it

Published on 2024-06-24 by Raul

I've been struggling for a while with IIS giving very random 403 errors, especially on pages with a lot of js files included. I searched everywhere for a solution, couldn't find it.

After some trial and error, I pinpointed the exact issue: an IIS extension called "Dynamic IP restriction", which was supposed to keep you safe from DDOS. I doubled the default settings allowed (from Deny Criteria section, Maximum number of concurrent requests to 20 and Maxumum number of requests to 50) and all is good.

I'm sure that there's at least one person out there with the same issue, so enjoy :)

Keep in touch


Hey there, I'm Raul, owner of CreativeCLR, a small consulting company.

Feel free to drop me any question you might have on this post using the comment section or the contact page.