The client hash used to cache a libmongoc client is currently computed by serialising the connection string, along with the options and driverOptions arguments to the MongoDB\Driver\Manager constructor. This causes problems when passing a manager object as part of the autoEncryption options, as the manager can't be serialised.

To work around this problem, a manager object in that particular option should be exchanged for that particular manager's client hash. This only works for a manager passed as part of the keyVaultClient option of autoEncryption, and should not traverse through all options at this time.