Why does XMRig say "unsupported algorithm"?

XMRig says “unsupported algorithm” when it is asked to mine using a method that your copy of the program does not recognize or cannot run. For Monero, the usual causes are an old XMRig version, a wrong algorithm setting, or a pool connection that sends the wrong kind of work.

What the message means

A mining algorithm is the set of calculations your computer performs to help secure a cryptocurrency network. XMRig must understand that algorithm before it can process mining jobs.

Monero uses RandomX, which replaced its older CryptoNight-based algorithms on November 30, 2019. In XMRig, Monero’s RandomX algorithm is named rx/0.

The error is not usually a sign that your processor is too slow. It points first to a mismatch between your software, your settings, and the work it receives.

Look at the lines immediately before the error. They can help you tell whether XMRig rejected a local setting or encountered a problem after connecting to a pool.

Check your XMRig version and build

An old copy of XMRig may not support the algorithm your pool requests. This is especially likely if you followed a tutorial written before Monero switched to RandomX.

• Check the version shown when XMRig starts.
• Use a current release from the official XMRig project.
• Choose the download that matches your operating system and processor.
• Avoid unofficial “boosted” miners or downloads shared through private messages.

A build is a particular compiled copy of the program. Custom builds can have algorithms disabled, so even a recent version number does not guarantee that RandomX support is included.

If you are using an old, separate GPU-only XMRig program, switch to the current main XMRig software. RandomX favors CPUs—the main processors in computers—and an old GPU miner is not a suitable replacement.

Check the algorithm and coin settings

Open the configuration file XMRig actually uses, usually called config.json, and inspect the relevant entry under pools.

For a normal Monero pool, these settings let XMRig select the algorithm based on the coin:

"algo": null,
"coin": "monero"

These are fields within a pool entry, not a complete configuration file. If your pool specifically requires an explicit algorithm, Monero’s identifier is:

"algo": "rx/0"

Do not substitute rx/wow, which is a different RandomX variant, or copy old cn settings intended for CryptoNight.

Also check your launch command, shortcut, or startup script. An algorithm supplied there may conflict with the file you edited. Restart XMRig after changing the settings.

Check what your pool is sending

A mining pool combines work from many miners. If your settings look correct but the error appears after connecting, verify the pool address and port against its current instructions.

You may be connecting to:

• A port intended for a different coin or algorithm.
• A switching service that assigns work your build does not support.
• An outdated mining proxy—a program that relays jobs between you and the pool.

Do not change memory or performance settings first. Huge pages and thread counts affect RandomX performance, but they do not add support for a missing algorithm.

The bottom line

Start with a current official XMRig build, then check for monero or rx/0 and the correct pool address and port. If the error continues, share your version and nearby log lines with support, removing wallet addresses, passwords, and other private details first.