> ## Documentation Index
> Fetch the complete documentation index at: https://vowena-dependabot-github-actions-actions-checkout-7.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# accept_migration

> Accepts a pending plan migration for a subscriber. Cancels the old subscription, creates a new one on the target plan, and sets a fresh token allowance.

```rust theme={null}
fn accept_migration(
    env: Env,
    subscriber: Address,
    sub_id: u64,
    expiration_ledger: u32,
    allowance_periods: u32,
) -> u64
```

Accepts a pending migration for a subscription. This cancels the old subscription, creates a new subscription on the target plan, and sets a fresh token allowance for the new plan's terms. Returns the new subscription ID.

***

## Parameters

| Name                | Type      | Description                                                  |
| ------------------- | --------- | ------------------------------------------------------------ |
| `subscriber`        | `Address` | The subscriber's Stellar address. Must sign the transaction. |
| `sub_id`            | `u64`     | The old subscription ID with a pending migration.            |
| `expiration_ledger` | `u32`     | Absolute ledger at which the new SAC allowance expires.      |
| `allowance_periods` | `u32`     | Number of periods the new allowance should cover.            |

***

## Authorization

```rust theme={null}
subscriber.require_auth();
```

Only the subscriber on the subscription can accept the migration. The subscriber's signature covers the `accept_migration()` call, the old subscription cancellation, and the new `token.approve()` for the target plan.

***

## Return value

`u64` - the new subscription ID on the target plan.

***

## Events emitted

| Event        | Topics                                   | Data              |
| ------------ | ---------------------------------------- | ----------------- |
| `mig_accept` | `subscriber`, `old_sub_id`, `new_sub_id` | Migration details |

***

## Error cases

| Code | Name                 | Description                                            |
| ---- | -------------------- | ------------------------------------------------------ |
| 9    | `Unauthorized`       | Caller is not the subscriber on this subscription.     |
| 12   | `NoMigrationPending` | No migration has been requested for this subscription. |

***

## Examples

<Tabs>
  <Tab title="SDK">
    ```typescript theme={null}
    import { VowenaClient, NETWORKS } from "@vowena/sdk";

    const client = new VowenaClient({
      contractId: NETWORKS.testnet.contractId,
      rpcUrl: NETWORKS.testnet.rpcUrl,
      networkPassphrase: NETWORKS.testnet.networkPassphrase,
    });

    // Accept the pending migration
    const tx = await client.buildAcceptMigration(
      "GSUBSCRIBER...ADDR",   // Subscriber's address
      oldSubscriptionId,       // Old subscription ID
      { allowancePeriods: 24 } // Optional allowance tuning
    );

    const signedXdr = await signTransaction(tx);
    const result = await client.submitTransaction(signedXdr);
    console.log("New subscription ID:", result.subscriptionId);
    ```
  </Tab>

  <Tab title="Soroban CLI">
    ```bash theme={null}
    soroban contract invoke \
      --id CONTRACT_ID \
      --network testnet \
      --source SUBSCRIBER_SECRET \
      -- \
      accept_migration \
      --subscriber GSUBSCRIBER...ADDR \
      --sub_id 1 \
      --expiration_ledger 3100000 \
      --allowance_periods 24
    ```
  </Tab>
</Tabs>

<Info>
  The new subscription inherits the subscriber's billing history context but
  starts fresh on the new plan's terms. The old subscription is permanently
  cancelled. The new allowance is calculated based on the new plan's
  `price_ceiling` and `max_periods`.
</Info>