The title says it all—if you have a Mac Studio powered by an M3 Ultra chip, you cannot upgrade to macOS 26 Tahoe at this time. macOS 15.7 Sequoia will install, or you can wait until Apple resolves the issue.
Apple has updated the Mac Studio for the first time since 2023, replacing the M2 Max and M2 Ultra chips with the M4 Max and M3 Ultra. The new models offer significant performance gains, increase maximum memory from 192 GB to 512 GB, boost storage limits from 8 TB to 16 TB, and add Thunderbolt 5 connectivity.