Early 2009 MacBook Pro OS update

The highest OS this system can support is OS-X El Capitan 10.11.6.

This series can only support a max of 8GB of RAM and the HD SATA port is only able to support a SATA II (3.0 Gb/s) drive. Make sure the drive you get clearly states it can support it. Most drives today are fixed speed SATA III (6.0 Gb/s) which will not work reliably. Some drives offer Auto sense technology adjusting there speed to the systems SATA ports I/O. As an example a Samsung 870 EVO SSD clearly states it on the Interface line: SATA 6 Gb/s Interface, compatible with SATA 3 Gb/s & 1.5 interfaces.