How to change blockchain configuration in Studio

Learn how to review and change on-chain configuration parameters on simulator networks and localnets

Available since: Acton 1.2

Change a configuration parameter to test fees, limits, or protocol settings. Studio provides the same editor for simulator and localnet. These changes affect the virtual blockchain, not Acton.toml or Docker settings.

Configuration changes affect the selected simulator network or localnet. Invalid fees or limits can prevent contract execution. Restore the prerequisite snapshot to recover.

Public networks do not allow changing the config in the UI and only provide its inspection.

Prerequisites

A running virtual environment.
The configuration parameter number and replacement value to test.
A snapshot of the original state.

Edit and apply a parameter

Open the environment's Network → Config page.
Find the parameter and select its edit control. Use Add parameter for a missing parameter.
Edit the supported Fields, or select Raw cell to enter a parameter bag of cells (BoC) in hex or base64. For a new parameter, enter its Parameter number first.
Select Review change and inspect the original and replacement values. Technical details shows the resulting cell and hash.
Select Apply to network and wait for confirmation. Open the linked masterchain block.

A simulator commits a configuration-only block even when automatic mining is disabled. A localnet submits the change through the network and waits for masterchain confirmation. The operation can continue after leaving the page.

Prepare the shared request file, then submit it to the simulator control API:

curl --fail http://127.0.0.1:5411/acton_setConfigParam \
  -H 'content-type: application/json' --data-binary @parameter-update.json

The control API reference defines the response format. Parameter 0 cannot be changed through this endpoint.

Prepare the shared request file. Use the authenticated control API connection, replacing <CONTROL_URL> and <CONTROL_TOKEN> with the selected service's values:

curl --fail '<CONTROL_URL>/v1/network/config' \
  -H 'Authorization: Bearer <CONTROL_TOKEN>' \
  -H 'content-type: application/json' --data-binary @parameter-update.json

The response accepts an operation; it does not prove the parameter is active yet. Replace <OPERATION_ID> with the returned id and wait:

acton localnet operation '<OPERATION_ID>' --network dev --wait

Prepare the CLI request

Neither environment has a dedicated configuration subcommand. Both control APIs accept parameter-update.json. For parameter 21, replace <PARAMETER_BOC> with the replacement base64 BoC and <CURRENT_HASH> with the current cell's lowercase hexadecimal representation hash:

parameter-update.json

{
  "index": 21,
  "boc": "<PARAMETER_BOC>",
  "expectedHash": "<CURRENT_HASH>"
}

Use "expectedHash": null only when adding a parameter that is absent.

Verify the change

Reopen Network → Config and inspect the committed value. Other parameters and historical configurations remain intact. If another edit changed the original cell, the expected-hash check rejects the stale update. Reload and review the current value before retrying.

How to change blockchain configuration in Studio

Prerequisites

Edit and apply a parameter

Prepare the CLI request

Verify the change

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