Some vendor patches for the Spectre and Meltdown CPU vulnerabilities have been causing problems for users. Microsoft said that systems running incompatible anti-virus products would not receive any further updates; anti-virus vendors must confirm compatibility by setting a registry key. Linux has released microcode to address the CPU problems for certain processors. Canonical had to release a new patch after Ubuntu Xenial 16.04 users reported that the first fix rendered their systems unable to boot. Google says it applied patches for the flaws last year and that they have not slowed down its cloud services.