I had a problem, and now a new one, very likely related.
For a while now I’ve gotten (and for RCs, that I could run):
$ juliaup default 1.12
Configured the default Julia version to be '1.12'.
but it wasn’t working (I just put off looking into that original problem), the default is still 1.12, but at least I could still run it manually, with (until no longer, I feel like I recall running 1.12.0, at least RCs worked):
$ julia +1.12
ERROR: The channel `1.12` does not exist in the versions database.
$ juliaup list
...
1.12.0-rc1 1.12.0-rc1+0.x64.linux.gnu
1.12.0-rc1~x64 1.12.0-rc1+0.x64.linux.gnu
1.12.0-rc1~x86 1.12.0-rc1+0.x86.linux.gnu
1.12.0-rc2 1.12.0-rc2+0.x64.linux.gnu
1.12.0-rc2~x64 1.12.0-rc2+0.x64.linux.gnu
1.12.0-rc2~x86 1.12.0-rc2+0.x86.linux.gnu
1.12.0-rc3 1.12.0-rc3+0.x64.linux.gnu
1.12.0-rc3~x64 1.12.0-rc3+0.x64.linux.gnu
1.12.0-rc3~x86 1.12.0-rc3+0.x86.linux.gnu
1.12.0~x64 1.12.0+0.x64.linux.gnu
1.12.0~x86 1.12.0+0.x86.linux.gnu
1.12~x64 1.12.0+0.x64.linux.gnu
1.12~x86 1.12.0+0.x86.linux.gnu
...
1.11 starts up 1.11.7 still, but suggest a downgrade…:
$ julia +1.11
The latest version of Julia in the `1.11` channel is 1.11.3+0.x64.linux.gnu. You currently have `1.11.7+0.x64.linux.gnu` installed. Run:
juliaup update
in your terminal shell to install Julia 1.11.3+0.x64.linux.gnu and update the `1.11` channel to that version.
Any idea how to debug this or what might have happened? File an issue or is it already known?
$ juliaup up
Checking for new Julia versions
Checking for new version on channel '1.11-nightly' is taking a while... This can be slow due to server caching
Checking for new version on channel 'nightly' is taking a while... This can be slow due to server caching
Updating channel nightly
GC: No unused Julia installations to clean up.
$ juliaup default 1.12
Configured the default Julia version to be '1.12'.
$ julia +1.12
ERROR: The channel `1.12` does not exist in the versions database.
$ juliaup st
Default Channel Version Update
---------------------------------------------------------------------
..
1.11.3 1.11.3+0.x64.linux.gnu
* 1.12 1.12.0+0.x64.linux.gnu
beta 1.12.0+0.x64.linux.gnu
lts 1.10.10+0.x64.linux.gnu
nightly Development version 1.13.0-DEV.1317
release 1.12.0+0.x64.linux.gnu
release~x86 1.12.0+0.x86.linux.gnu
$ julia
The latest version of Julia in the `1.10` channel is 1.10.8+0.x64.linux.gnu. You currently have `1.10.10+0.x64.linux.gnu` installed. Run:
juliaup update
in your terminal shell to install Julia 1.10.8+0.x64.linux.gnu and update the `1.10` channel to that version.
..
| | |_| | | | (_| | | Version 1.10.10 (2025-06-27)
This file is not ordered, maybe that’s the problem? [Maybe related to “Dict”/“HashMap is inherently unordered” like in Julia, unlike by now in Python?]
Note by now I can run 1.12.1 after installing it (and actually 1.12.0 started working again too) after:
$ juliaup default 1.12.1
Configured the default Julia version to be '1.12.1'.
Worked the other day, don’t recall anything I’ve done since. It keeps acting strangely despite both installed…:
$ julia +1.12
ERROR: The channel `1.12` does not exist in the versions database.
$ julia +1.12.1
ERROR: The channel `1.12.1` does not exist in the versions database.
$ juliaup remove 1.12.1
$ juliaup remove 1.12
Deleting symlink julia-1.12.
Tidyup No unused Julia installations to clean up.
Remove Julia channel '1.12' successfully removed.
$ julia +1.12.1
ERROR: The channel `1.12.1` does not exist in the versions database.
$ juliaup update
Checking for new Julia versions
Updating channel 1
Updating channel beta
Updating channel release~x86
Installing Julia 1.12.1+0.x86.linux.gnu
Updating channel release
Updating channel nightly
Tidyup Removed Julia 1.12.0+0.x86.linux.gnu
Tidyup Removed Julia 1.12.0+0.x64.linux.gnu
$ julia +1.12.1
ERROR: The channel `1.12.1` does not exist in the versions database.
It seems that you now have only channels release, nightly, beta, and 1 installed. Note that while the release channel is Julia v1.12, so v1.12 is present, the channel 1.12 properly is not. It would be if you did juliaup add 1.12 (that would link the channel 1.12 to same binary that channel release).
Check all that is installed with juliaup st, then add channels that you want. Remind that channels point to binaries but are not binaries, only link to them.