Philips just released firmware for the Philips Hue bridge that may permanently sever access to any “non-approved” ZigBee bulbs. We previously covered third party support in January 2015, when Philips indicated it was not blocked – and have since benefited.

Source: Philips Hue Excludes 3rd Party Bulbs With Firmware Update

Sometimes it’s better never to upgrade firmware.  Don’t fix what isn’t broke.  As a general rule firmware should never need upgrading.