Lcb_err_unsupported_operation (214)

Based on the documentation

not sure it is the same on the php as the documentation for PHP is incomplete

if I add the ?kv_timeout=250 to the connection string I get the error: Failed to initialize LCB connection: LCB_ERR_UNSUPPORTED_OPERATION (214)

now my connection string is something like:

$connstring = ‘couchbase://SRV1, SRV2,SRV3,SRVn?kv_timeout=2500’

this connection string is used like this

$options = new \Couchbase\ClusterOptions();
$options->credentials($username, $password);
static::$cluster = new \Couchbase\Cluster($connstring, $options);

if I use the ?query_timeout=10000 it seems to work corectly

What I am doing wrong?