Each problem below comes with one fix. For Unreal Engine problems, see Unreal Engine.

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Builds

Your build’s status is failed. Open the Builds tab. The build shows an error message that says what went wrong. Fix that, then upload the build again. A Docker image build fails because it has no linux/amd64 version. Build the image again with --platform linux/amd64, push it, and register it again. A Docker image build fails because the image was not found. Check the image name and tag in image_url. If the image is private, add registry_username and registry_password.

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Starting servers

Starting a server fails with PLAN_LIMIT_EXCEEDED. On the Free plan, use size 1x-1g in region iad, run one server at a time, and keep ttl at 30 minutes or less. For more, change your plan. See Plan Limits. Starting a server fails with PAYMENT_METHOD_REQUIRED. Add a card to your account. The PAYG and Pro plans need one. Starting a server fails with BUILD_NOT_READY. Wait until the build’s status is ready, then try again. A server stops after 30 minutes. That is the Free plan’s limit. Change your plan to run longer.

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Connecting

Players can’t connect to a running server. Make your server listen on the port in SIMPL_PORT_GAME and use the address in SIMPL_UDP_BIND_ADDRESS (UDP) or SIMPL_TCP_BIND_ADDRESS (TCP), exactly as given. A browser game also needs wss:// and the host name: see Browser games (wss://). See Ports and environment. Players connect to the wrong port. Players must use the server’s external_port, not the port your server listens on. See Connect players.

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Logs

You can’t see any logs for your server. Make your server write its logs to the console (standard output). Simpl shows what your server prints there. Open them from the Servers tab.

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Requests

Requests fail with 429 and RATE_LIMITED. You sent too many requests. Wait for the number of seconds in the Retry-After header, then try again. See Rate Limits.