I tried to upgrade to Monterey and got the message storage system verify or repair failed: 69716. What does this mean?

I have this problem upgrading from 10.4.6 Mojave with a 1 TB Fusion disk.

I have tried rebooting in safe mode and using the Disk Utility, but there is nothing wrong with the disk. But this comment stream makes the most sense I have seen. When I hold on to the Options key, I see only Macintosh HD and my time machine external hard drive as options.

I tried upgrading to Catalina, but Apple has only 10.15.1 and 10.15.7 available and they both require that you have Catalina 10.5.0 installed.

Everything is Apple original inside the computer (only a external hard drive is connected for Time Machine backups).

I don't use FileVault.

I found that and tried it earlier. It did not say "Safe mode" on the upper right hand corner, but I did check that it did not load the 3rd party icons. I did the update from there and it was the same error.

Thanks both max1demian and LLLaass.

I actually only need to go up to Catalina so a program would run. But my iMAC wanted me to go to Monterey. After that had failed, I tried downloading (via Apple website) 10.15.7 and 10.15.11 but they said 10.5.0 was a requirement to run.

BUT, with the link lllaass sent, I was able to click on it and instead of downloading a file, it opened up my App Store and came with MacOS-loader. That did not require me to be on Catalina already and that upgrade from 10.14.5 to 10.15.7 worked like a champ! Thanks so much. I did not want to refresh my hard-drive and trust to my backups to restore everything.

As I wrote, I'm using macOS Mojave and that system works with APFS volumes. With that file system, it is easy to add a new volume (80 Gb) and that's what I did to have a volume for a fresh install of Big Sur for testing.