Troubleshooting

The usual problems, and what to try first.

A backtest will not start

OK is greyed out. The window says why: not enough compute units, or Every tick on a plan without it. See Plans and credits.
It starts, then errors. Open its Log. A backtest stops at the first error in your code. See Debug an algorithm.
“Instrument ‘…’ is not available.” The algorithm names an instrument in INSTRUMENTS[...] that this broker does not offer. Check the spelling, including the broker after the colon, such as EUR/USD:FXCM.

Errored. You get an email with the error and its positions. Fix the code, save a new version, and start a new session.
Three errors within 60 seconds end a session. One error is logged and the session carries on.
Too many orders. A session ends if it asks for 50 positions within a minute or opens 500 in total.
Weekend. From Friday 22:00 to Sunday 22:00 UTC sessions sleep, and the status detail says so. That is not a stop.
OK is greyed out in New Trading Session. Your plan has no trading sessions.

“… connections are retired.” That broker or exchange has been retired. Its price history stays for backtests; delete the saved key. See Brokers.
“Could not validate. Please contact support.” Saving keys for Binance in Exchange API Keys is not available yet. See Brokers.
An error under the key’s row. The broker refused the key, for example because it expired or lacks permissions. Delete it and add a new one.
Test connection fails. Check each detail with your broker, and that the account is a demo or practice account.

Email support@cloud9trader.com with what you did, what you expected, and the time it happened. Never send your password or API secret.