How-to
Canister Out of Cycles: What Happens and How to Fix It
Cycles are prepaid fuel. When the balance hits zero, updates stop and the canister can freeze. Topping up with ICP through the CMC restores fuel — you do not need to be a controller to top up.
September 5, 2026 · 8 min read
What “out of cycles” means
- Update calls fail or the canister stops accepting state changes
- Idle burn still applies while memory is reserved
- Prolonged emptiness risks reclaim — treat empty balance as an incident, not a warning
How to fix it (ICPay)
- Open icpay.app/topup (or Top up from My canisters).
- Paste the canister ID and an ICP amount.
- Confirm — ICPay sends ICP to CMC with the top-up memo and notifies
notify_top_up. - Controllers can verify the new balance under Manage.
How much ICP to send
Top-up has a low minimum (far below create). Size deposits to days or weeks of idle burn plus expected traffic. Busy canisters burn faster. Preview estimated cycles before you confirm.
Prevent it next time
- Check cycles regularly if you are a controller
- Keep a buffer on the cycles ledger to withdraw quickly
- Top up after big upgrades or traffic spikes
