🏆 FINAL UPDATE (June 2026) – THE MYSTERY IS SOLVED & MOJAVE IS SAVED! (Huge thanks to the community!)

I wanted to share the final, chronological breakdown of our tests and the ultimate solution to run Backblaze on macOS 10.14 Mojave. The community has been absolutely incredible in mapping this out step-by-step.

• Step 1: The initial v10 roadblock We started by trying to install the current official v10 client. Despite Backblaze’s Info.plist metadata claiming compatibility down to macOS 10.13 (LSMinimumSystemVersion = 10.13), the installer instantly crashed on launch on Mojave with an Abort trap: 6 error. Running the binary via Terminal indicated that the build relies on modern frameworks (like SwiftUI) which physically require macOS 10.15 Catalina or newer to execute.
• Step 2: Testing the v8.5 branch (Thanks to u/ampx**!)** To see if we could bypass this framework crash, u/ampx provided a legacy v8.5 installer. This was a crucial first step: the application launched perfectly and the UI rendered flawlessly, proving that older builds run natively on Mojave without crashing. However, when entering account credentials, it triggered a server-side block: "The installer has determined it is unable to continue..."
• Step 3: Testing the early v9 branch (Thanks to u/tomierna**!)** To determine if a slightly newer handshake would pass, u/tomierna dug into their download archives and provided a v9.0.1 installer. The UI opened beautifully without crashing, but it hit the exact same server-side authentication wall upon logging in. Backblaze has strictly updated their server security requirements, dropping support for v8 and early v9 handshakes.
• Step 4: THE ULTIMATE SOLUTION (Huge thanks to u/heff66**!)** Just as we thought we were stuck in a deadlock, u/heff66 came to the rescue and shared a link to the v9.2.2.888 installer revision. The results are flawless: The v9.2.2 installer opened perfectly without the v10 SwiftUI crash, AND its authentication protocol is modern enough to be accepted by Backblaze's servers! The login went through instantly, I received the official confirmation email from Backblaze, and bzfilelist is currently running smoothly, actively scanning my multi-terabyte drives for the initial backup setup.

Summary for legacy users: If you need to perform a fresh install or a re-authentication on macOS 10.14 Mojave, do not use the v10 installer. Instead, track down and use the v9.2.2.888 installer. It is the sweet spot that avoids the modern framework crash while remaining perfectly compliant with Backblaze's active authentication servers.

A massive, heartfelt thank you to u/ampx, u/tomierna, and u/heff66. Each of you provided a vital piece of the puzzle that allowed us to figure this out! 🚀

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🎯 FINAL UPDATE (June 8, 2026) – THE MYSTERY IS SOLVED (THE DEADLOCK IS REAL & SUPPORT IS USELESS)

It is wild how many vendors have adopted this exact same "silent bricking" approach lately. You follow their own instructions for legacy systems, and instead of a working binary, you get a glorified error message because they couldn't be bothered to host a static legacy DMG link.

Losing a Backblaze backup state and having to re-upload everything from scratch over an OS upgrade is the absolute icing on the cake. Good on you for keeping that old DMG safe on a drive—at this point, hoarding old installers is becoming a critical sysadmin survival skill.

For anyone tracking this, here is the complete technical timeline of our tests with the community:

• Step 1: The initial v10 roadblock – We started by trying to install the current official v10 client. Despite Backblaze’s Info.plist metadata claiming compatibility down to macOS 10.13 (LSMinimumSystemVersion = 10.13), the installer instantly crashes on launch on macOS 10.14 Mojave with an Abort trap: 6 error. Running the binary via Terminal indicated that the build relies on modern frameworks (like SwiftUI) which require macOS 10.15 Catalina or newer to execute.
• Step 2: Testing the v8.5 branch (Thanks to u/ampx!) – To see if we could bypass this framework crash, u/ampx provided the legacy v8.5 installer. This was a crucial first step: the application launched perfectly and the UI rendered flawlessly, proving that older builds run natively on Mojave. However, when entering account credentials, it triggered a hard block: "The installer has determined it is unable to continue..."
• Step 3: Testing the v9 branch (Thanks to u/tomierna!) – To determine if a slightly newer handshake would pass, u/tomierna dug into their download archives and provided several v9 binaries along with the v9.0.1.768 DMG installer. The result was identical to v8.5: the v9.0.1 interface opened beautifully without crashing, but it hit the exact same authentication wall upon logging in.
• Step 4: The hybrid attempt – We attempted a final workaround by extracting the newer 9.1.0 binary from u/tomierna's files and injecting it into the v9.0.1 installer package. However, macOS Gatekeeper logically and rightfully blocked the application due to modified code-signing.

Technical Conclusion & Support Nightmare: There is currently a technical standstill for fresh installations or new account re-authentications on macOS 10.14 Mojave. While older clients (v8/v9) run perfectly on the OS, Backblaze's authentication servers have strictly updated their security and protocol compliance requirements, meaning they no longer accept registration handshakes from legacy clients.

To make things even worse, I am currently locked in a support loop with them and their Tier 1/2 support is absolutely abysmal. I literally proved to them, logs and Terminal outputs in hand, that their current V10 installer instantly crashes because of their own sloppy framework bundling. Given that I am currently using version 9.2.2.898, I know for a fact the V9 branch works perfectly, so I asked support to escalate this and simply transfer or authorize my paid licence on this working build. They flat out refused. They are actively trying to force me onto a V10 client that I just demonstrated doesn't even work on this OS, choosing corporate stonewalling over 5 minutes of actual technical support for a paying customer. They’ve clearly opted for the FOAD method.

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