When MacRumors contacted for clarity, Apple said that the add-on enhances system stability and reliability across multiple sites, addressing multiple issues, including cracking audio and core panels. Apple said it is recommended that all users install the update on MacBook Pros.
The 1.3 GB update has not been available long enough, but for some crucial evidence from affected users, with mixed reports of Apple Support Communities, Reddit and our own MacRumors discussion forums.
Apple Support Communities user takashiyoshida, for example, claimed that the MacBook Pro "no longer perform cracking sound" after updating.
"Tonight I put the microphone and speakers sampling format to 441
Reddit user onceARMY commented, however, that he "still received sound-blazing noise while playing YouTube content on Safari." He noticed that there were "no problems with the Spotify app" after you installed the update.
As for core panels, a handful of users have reported to experience at least one since the installation of the additional update.
"Installed today's update … and so it happened," wrote MacRumor's forum member King724, referring to a kernel panic. He shared a log indicating a bridgeOS system crash, the firmware on the logic board that controls many features of the 2018 MacBook Pro, including the Apple T2 chip.
Last month, Apple said there was a small number of indirect reports about the nuclear panics, but would not say if the T2 chip was blaming.
Similar kernel panning reports began last year with iMac Pro, which is also equipped with T2, so it did – or maybe still – seem to be a potential issue with the chip or bridge firmware that manages it. There was some speculation that the T2 chip was also blamed for crackling.
For context, the T2 integrates several earlier separate components, including system administrator, image signal processor, audio controls, and SSD controllers. It also has a Secure Enclave coprocessor for secure boot, encrypted storage and authentication of Touch ID.
Before yesterday's additional update, Apple representatives provided customers with a wide range of possible solutions to reduce these issues, from disabling FileVault to turn off Power Nap, but none of the solution seemed to resolve the issues permanently.
Apple also asked some customers if they would be willing to submit MacBook Pros so engineers can look into the issues. Some customers were clearly told that repairs were in the work, and at least based on what Apple told us, they are included in the additional update.
This is the second MacOS High Sierra Supplemental Update for the 2018 MacBook Pro for so many months, with the first address of an error that contributed to excessive throttle under clear thermal loads.
The Complementary Update is not available for MacOS Mojave users, but the issues can be solved in future beta versions.