"Request failed with status code 500" / 403 when installing a mod — how do I fix it? — Minecraft

Q: The manual upload worked but the mod isn't loading. Why?

Confirm it's in the mods folder, matches your Minecraft version and loader, and that any required dependency mods are present too. Then restart and check the Console.

Seeing "Request failed with status code 500" or a 403 when installing a mod can look alarming, but it isn't your server crashing. It means the installer couldn't fetch the file from the upstream source (CurseForge or Modrinth). Here's how to get past it.

Why this happens

The Mods installer reaches out to an external catalog to download the .jar for you. A 500 usually means that source is briefly overloaded or rate-limiting, and a 403 means it temporarily refused the request. Either way, the problem is on the download side, not your server.

How to fix it

Wait a minute and retry. The source may be briefly rate-limiting (500) or blocking (403), and a short pause often clears it.
Make sure the server is stopped in the Console and that you have free disk space for the download.
Install manually if it keeps failing. Download the mod .jar yourself from CurseForge or Modrinth, then upload it into the mods folder via the Files tab (or SFTP for large files).

Tip: When you upload a mod manually, double-check it matches your server's Minecraft version and loader (Forge or Fabric) — the Mods tab normally filters that for you.

Frequently asked questions

Does this error mean my world is damaged? No. Nothing was written to your server — the download simply didn't complete.

The manual upload worked but the mod isn't loading. Why? Confirm it's in the mods folder, matches your Minecraft version and loader, and that any required dependency mods are present too. Then restart and check the Console.

Can staff install it for me? If you're stuck after trying the steps above, open a ticket with the mod name and version and we'll help.