Apple Seeds Third Beta of Upcoming macOS Catalina 10.15.3 Update to Developers

Apple today seeded the third beta of an upcoming macOS 10.15.3 update to developers for testing purposes, one week after seeding the second beta and more than a month after releasing the macOS Catalina 10.15.2 update.

The new ‌‌macOS Catalina‌‌ beta can be downloaded using the Software Update mechanism in System Preferences after installing the proper software from the Developer Center.

macos catalina wallpaper
We don't yet know what improvements the third update to macOS Catalina will bring, but it will likely focus on performance improvements, security updates, and fixes for bugs that weren't able to be fixed in the macOS Catalina 10.15.2 update.

macOS Catalina‌ 10.15.3 has code in it that suggests a new "Pro Mode" is coming to Apple's Macs. Pro Mode appears to be an optional setting that overrides fan speed limits and energy saving restrictions to improve performance. The code says that apps "may run faster" but battery life could decrease and fan noise could increase.

It's not entirely clear if Pro Mode is coming to Macs in the 10.15.3 release, but the code is there so it is a possibility.

We didn't find any other major new changes in the first two betas of macOS Catalina 10.15.3, but we'll update this post if there's anything new in the third beta.

Related Forum: macOS Catalina

Popular Stories

iPhone 17 Pro Dark Blue and Orange

iPhone 17 Release Date, Pre-Orders, and What to Expect

Thursday August 28, 2025 4:08 am PDT by
An iPhone 17 announcement is a dead cert for September 2025 – Apple has already sent out invites for an "Awe dropping" event on Tuesday, September 9 at the Apple Park campus in Cupertino, California. The timing follows Apple's trend of introducing new iPhone models annually in the fall. At the event, Apple is expected to unveil its new-generation iPhone 17, an all-new ultra-thin iPhone 17...
iPhone 17 Pro Iridescent Feature 2

iPhone 17 Pro Clear Case Leak Reveals Three Key Changes

Sunday August 31, 2025 1:26 pm PDT by
Apple is expected to unveil the iPhone 17 series on Tuesday, September 9, and last-minute rumors about the devices continue to surface. The latest info comes from a leaker known as Majin Bu, who has shared alleged images of Apple's Clear Case for the iPhone 17 Pro and Pro Max, or at least replicas. Image Credit: @MajinBuOfficial The images show three alleged changes compared to Apple's iP...
iphone 16 pro ghost hand

iPhone 17 Pro: 5 Reasons Not to Upgrade This Year

Monday September 1, 2025 4:35 am PDT by
Apple will launch its new iPhone 17 series this month, and the iPhone 17 Pro models are expected to get a new design for the rear casing and the camera area. But more significant changes to the lineup are not expected until next year, when the iPhone 18 models arrive. If you're thinking of trading in your iPhone for this year's latest, consider the following features rumored to be coming to...
xiaomi apple ad india

Apple and Samsung Push Back Against Xiaomi's Bold India Ads

Friday August 29, 2025 4:54 am PDT by
Apple and Samsung have reportedly issued cease-and-desist notices to Xiaomi in India for an ad campaign that directly compares the rivals' devices to Xiaomi's products. The two companies have threatened the Chinese vendor with legal action, calling the ads "disparaging." Ads have appeared in local print media and on social media that take pot shots at the competitors' premium offerings. One...
iOS 18 on iPhone Arrow Down

Apple Preparing iOS 18.7 for iPhones as iOS 26 Release Date Nears

Sunday August 31, 2025 4:35 pm PDT by
Apple is preparing to release iOS 18.7 for compatible iPhone models, according to evidence of the update in the MacRumors visitor logs. We expect iOS 18.7 to be released in September, alongside iOS 26. The update will likely include fixes for security vulnerabilities, but little else. iOS 18.7 will be one of the final updates ever released for the iPhone XS, iPhone XS Max, and iPhone XR,...

Top Rated Comments

AppleMatt Avatar
73 months ago
Good news with this update:

https://forums.macrumors.com/threads/psa-apple-mail-bugs-can-lead-to-data-loss-in-macos-catalina.2205346/post-28158834

Attachment Image
Score: 11 Votes (Like | Disagree)
ruslansv Avatar
73 months ago

And once again is the most important question: Has Apple finally fixed the Mail data loss bug?
Why does Apple stubbornly refuse to list what is fixed and what is not fixed (or targeted to a different release) via proper release notes (and not a joke of release notes they're providing)?
Score: 10 Votes (Like | Disagree)
macdos Avatar
73 months ago
It would be insanely great if Apple devotes some effort to maximize performance and minimize memory consumption. We should not have to rely on Macfanscontrol and Lingon to control fan speed and disable unncessary daemons, it should be builtin, as in Windows.
Score: 6 Votes (Like | Disagree)
grandchester Avatar
73 months ago
Hope it fixes the iCloud verification finally. Real tired of entering iCloud and Mac passwords AND the code on my iPhone for some reason every other day.
Score: 5 Votes (Like | Disagree)
sugargliderdude Avatar
73 months ago
think I'm going to install Catalina 10.15.3 once its released to the public
Score: 4 Votes (Like | Disagree)
bsbeamer Avatar
73 months ago
Really hope this release fixes the AMD 5XXX series drivers for MBP16,1 5500M and RX 5700 & RX 5700 XT in eGPU. Every video software vendor is pointing to those drivers as the reason for METAL issues with their software that disappear with RX580 or go software only.
Score: 4 Votes (Like | Disagree)