# X_TEST_DRIVER_CLIENT_CHANGED

## Means

The installed client changed inside a testDriver() transaction

## Typical cause

setDbClient installed or cleared a client while a transaction opened through testDriver() was still running, so its writes would land in two stores

## Fix

`beforeAll(() => setDbClient(client)); afterAll(() => setDbClient(undefined));   # outside every transactor().run / withTransaction scope`

[Entity and database](/error-codes#entity-and-database)