How to retrieve cycles from an abandoned canister

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1

Note that this guide uses dfx version 0.8.1

  1. Create a new identity using
dfx identity new move_cycles
  1. Use the identity created by issuing
dfx identity use move_cycles
  1. Save the principal ID of the move_cycles identity to the environment variable MOVE_CYCLES_IDENTITY by running
MOVE_CYCLES_IDENTITY=$(dfx identity get-principal)
  1. Use the previous identity that is controller of the wallet canister that controls the abandoned canister by issuing the following command and substituting <your_old_identity> accordingly
dfx identity use <your_old_identity>
  1. Make the move_cycles identity the controller of the abandoned canister.
    Make sure you run this command from within a dfx project folder and edit the canister_ids.json file so that the canister id of the abandoned canister is present. If your canister_ids.json file contains those entries,
{
  "assets": {
    "ic": "kwflp-viaaa-aaaae-aaaaa-cai"
  },
  "kanban": {
    "ic": "kren3-yqaaa-aaaae-aaaaa-cai"
  }
}

replace one of the canister ids with the id of the abandoned canister like this

{
  "assets": {
    "ic": "<abandoned_canister_id>"
  },
  "kanban": {
    "ic": "kren3-yqaaa-aaaae-aaaaa-cai"
  }
}

Then run

dfx canister --network ic update-settings --controller $MOVE_CYCLES_IDENTITY <abandoned_canister_id>
  1. Now that the move_cycles identity is the controller of the abandoned canister, switch back to it by issuing
dfx identity use move_cycles
  1. Run the following command to uninstall the canister
dfx canister --network ic --no-wallet uninstall-code <abandoned_canister_id>
  1. Now run the following command to deploy a cycles wallet to the now empty canister
dfx identity --network ic deploy-wallet <abandoned_canister_id>
  1. Finally you can either send cycles to the cycles wallet of your main identity by issuing the following command or accesing the cycles wallet frontend under <abandoned_canister_id>.ic0.app and following the instructions on screen
dfx wallet --network ic send <main_cycles_wallet_id> <amount_of_cycles_to_send>
  1. If you want to you can now stop the wallet canister after you moved the cycles by running
dfx canister --network ic stop <abandoned_canister_id>

and

dfx canister --network ic delete <abandoned_canister_id>
  1. If you no longer need the move_cycles identity you can also remove it by issuing
dfx idenity remove move_cycles
6 Likes
2

dfx canister --network ic --no-wallet uninstall-code XXXXXXXXXX
the replica returned an HTTP Error: Http Error: status 403 Forbidden, content type “”, content: Requested canister rejected the message， why??

3

Did you make sure you changed your dfx identity as described in step 6?

4

Is this still applicable? Seems rather complicate to take back some cycles from a canister.

5

no, you can now simply run
dfx canister --network ic stop <canister id>
and then
dfx canister --network ic delete <canister id>

1 Like
6

If you have a canister controlling another canister (and you use cross-canister calls to create, manage, and delete child canisters) can you still just stop and delete a child canister to get the cycles back? I’m assuming perhaps not?

7

You need to first have a method on the child canister that calls deposit_cycles and deposits the cycles back into the parent canister.

Then you can stop/delete the canister after.

2 Likes
8

Yeah, I assumed I would need to manually send the cycles back first, but it would be nice if you could “delete_and_reclaim_cycles” in a single command. Not the end of the world though.

Thanks!