Cannot Upload Media / IIS 10 / 502.6 & 502.3

System Information
  • Strapi Version: 4.14.4
  • Operating System: Windows Server 2022
  • Database: MySQL
  • Node Version: 16.17.0
  • NPM Version: 9.6.7
  • Yarn Version: N/A

I am having an issue with uploading files to my Strapi instance. I get a “bad gateway” error 502.6 whether trying through the front end or via the /api/upload endpoint using Postman. I am using a default Strapi install; no other upload providers are installed.

I developed mostly with a sqlite database, but moved over to MySQL recently. I don’t recall having this problem before the MySQL adoption.

IIS is acting as a reverse proxy to my Strapi instance. The instance itself I manage through PM2. PM2 logs do no even log the POST attempt (see image). The reverse proxy seems to be otherwise working fine. IIS logs give me the substatus “.6” for the 502 error on POST /upload, along with an error code 12303 which is undefined in the MS documentation.

Any thoughts other than dump IIS? I am so close to deployment that I don’t want to even entertain that possibility.

Apparently IIS_IUSRS needs write permission to C:\Windows\Temp. Once enabled, I was able to follow error messages in PM2.