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[@salesforce/b2c-tooling-sdk](../../modules.md) / [clients](../index.md) / createMrtMaintenanceMiddleware

# Function: createMrtMaintenanceMiddleware()

> **createMrtMaintenanceMiddleware**(): `Middleware`

Defined in: [packages/b2c-tooling-sdk/src/clients/mrt.ts:156](https://github.com/SalesforceCommerceCloud/b2c-developer-tooling/blob/1dedfc1ffefa01c3d5bff62c8f7e7e682a1a91cd/packages/b2c-tooling-sdk/src/clients/mrt.ts#L156)

Read-only mode handling, installed by [createMrtClient](createMrtClient.md) and [createMrtB2CClient](createMrtB2CClient.md):
rejected writes throw [MrtMaintenanceError](../classes/MrtMaintenanceError.md); reads notify the active
[runWithMrtReadOnlyListener](runWithMrtReadOnlyListener.md) listener; superuser writes (2xx) pass through.

## Returns

`Middleware`