When the SCO connection is in use, if you disconnect first and then connect, the SCO connection will occasionally fail, and the Bluetooth error code is 42 (0x2A in hexadecimal). This is usually because an error occurred when the SCO connection was initiated, we need to try to reconnect to optimize the handling of this problem. The log returned by the kernel is as follows:
Bluetooth: sco_connect_cfm: hcon 0000000003328902 bdaddr 40:ef:4c:0c:11:f0 status 42 Bluetooth: sco_sock_connect status is -38