AX, fix this issue and lunch is on me.
I have tree HDD, with a single OS and each. I try not to comingle.
The only multi boot dat I understand, was in basic training.
Installtion Issue
blueicetwice ......in my limited understanding, the bios just guarantees a Grub install (I think) and Solus would meke the Grub partition itse;f..still don't see the correlation.
It is utterly mindbogglind to me that Solus tells you installation was a success on boot then aborts on launch...
To me this means one of two things:
1) incompatible Graphics card (longshot)
2)Or more likely Axios is right: the other jealous distros are interfering. My advice is UNPLUG the other two then boot solus again. I am predicting success. Something is goofy in the boot then if what you say (Solus says install was successful) is correct.
Hang in there. this distro is well worth it and I've tried most.
D/Led GOGONOME and was told the installation was successful. Fabulous how the
screen slowly fads into darkness ! Brilliant engineering.
Upon restart, the issue again, Solus was not in the boot up order, even tho it was listed
in the Grubhub Customizer.
It has been a joy to communication with y'all, butt this is truly a waste of time, despite
being on home detention. 
: <---------- my imoji are blockheads : - ))
Operation UNPLUG, will commence ASAP, Major Brent. I thinkus the Ax is correctoe.
blueicetwice reinstall with others unplugged was probably the better suggestion, but all good.
"D/Led GOGONOME and was told the installation was successful." I don't know what means. The installer usually says at the end something like 'solus installed successfully'; or similar so if that's where you saw it...then grandiose
Brent, what dat means the installation was successful, according to
ISO d/l disc.
I did another install and Solus populated the boot up order. Den,
which I click the Solus boot line I got this: "ERROR: file /Das Boot/Solus Project.
current.6.3.8-240 not found"
ERROR: you need to load Lt. Kernel first.
Another dead end ! : - ( Next try, I will UNPLUG the two other HDD and the ninth
reinstall. In the meanwhile, time for dinner. The wifi is serving stir fried hard drive,
with stuffed Chinese Dram.
I did to fail to mention, I am installing on an HDD with Manjaro on it, but dat
should not make a difference.
blueicetwice did to fail to mention, I am installing on an HDD with Manjaro on it, but dat
should not make a difference.
'Sometimes' it makes a difference is my cryptic answer to that. you never know til you know. e.g. a partner OS installed with Grub will unceremoniously mug, then disappear, Solus' UEFI bootloader (if installed that way) about 8 times out of 10 if I had to guess and 10/10 for me personally (that's why separate drives per OS for me). Maybe it was Manjaro in the cellar with a candlestick (to bludgeon a Clue metaphor) the whole time?
"Maybe it was Manjaro in the cellar with a candlestick (to bludgeon a Clue metaphor) the whole time?" LOL, LOL
(that's why separate drives per OS for me) ditoes for me, as well, Brent.
If Solus has a UEFI bootloader, den dat may explain the problems, since my mama board is
not compatible.
Hear, is what happen last night. I disconnected the other two HDD, as per your instruction
and holey heck, the installation was successful, even after a fresh bootie. Watching the boot
lines, I noticed that the boot for Microgates 7 and Minty Mint were absence. To
quote Ms Greta Thunberg, "this is all wrong."
When I had only the Mint HDD plug in, the old bootloader lines appear !! Unfortunately, Solus
bootloader was not present. : - (( I now suspect it is not Solus fault, but rather my dated Mama
board. It is likely, I will have issue with other Linux discos, as well.
Brent, tanks for your support and the others, whom had commented. I have boarded an engine
power vessel, thus allowing Solus to sail to its next destination, less my baggage.
PS: This was not an issue, when I installed Solus some ten years ago.
blueicetwice Solus defauklts to UEFI install but can be made (in the installation GUI I believe) to installal GRUB boot instead. I have never tried this.
Either way, I agree, you tried.
Axios yep it's happened to me with linux and windows. Solus get's bullied a lot in my experience, probably because efi bootloaders is alien to most things grub and also to windows who has a bootloader...although I saw a single instances here recently where someone claims Solus wrecked all their other existing boots but I've never seen that. Strange times!
9 days later
UPDATE for my mates.
I tried two more installations and botf failed. Since Mint took a powder on me,
I decided a last attempt, with Solus 4.5 XFCE. Now the installation was NOT
a dual bootie, but a single installation on the entire HDD.
HOLEY VACA [COW] <---- Latin, it not only did it install, but bootied up as well !!!!!!!!!!!!!!!! :<))
Brent, was right about the problems with dual OSs, on a single drive. Same issue when da wifey
is driving.
The grubhub found itself on another HDD, so it required the change in HDD start up order. I bet if
I try to reinstall MInty 20 next to Solus, it will fail too.
The installer is the BEST I have ever used; quick, easy and with clear instructions. Mint installer, [21.3]
is rather AARPish and much slower. And it was not the UEFI nor the advanced kernel, which
I speculated as to the issue, in this twelve-year-old rig.
I wonder what I should do with MInt ??? There is an orphanage just three miles from me.
I used to bee Solus, until I got married.
I should add, dat Solus was installed as an EFI. None of my
other partitions have this classification. No DEI installations,
tank goodness.
Five stars to Brent on Google Map, for his suggestion, which lead
to this success !!
After three days of labor, my rig is up to par !!!! Solar installed with Mint 20 and Mint 21.
The Linux OSs welcome each other on an HDD, with operating OSs. In the meanwhile,
Mint 20 was still having issues with the network womanager; which resulted in me
breaking the OS. Too many modifications. I should add, Solus removed MicroGates7
from the bootloader. :<))
I reinstalled Mint 20 and den Mint 21, next to Solus. Then I discovered dat the Grubhub was
all messed up, as no HDD would boot. Oh dear, what have I done or undone ? The nightmare
was going to continue into a daymare. I call my old friend, Ronny Rescatux, whom said he
would arrive shortly, after break-fast. The first attempt failed, I lamented. Rescatux moved
to the second option, which should have been the first; perhaps it was the excess maple syrup
on his bits ?
I held my breath, as the rig bootied. Holey vaca, there it was, ALL THE BOOT OPTIONS !!!!!
https://www.supergrubdisk.org/2014/05/21/super-grub2-disk-2-00s2-downloads/#comments
I now have four Linux OSs and one MicroGates 7, on three HDDs. This was quite an experience [experepain?].
I did add to my knowledge base, despite the fact that my wife [wifi], was screaming at me to leave
the Linux bunker or she would give me Das Boot.! I assured her I would, after one more frontal attack.
PS: No HDD(s) were disconnected during this medical tech procedure.
**that you worked so hard to get Solus running, and succeed, just to purposefully sabotage yourself again and foul it up with a grub distro is so Linux Spirit Award 
.I try to do this once a year to stay sharp.
**don't go to the trouble of orphanage, just leave Mint on the curb for the coyotes. (natural order).
**Holy Vaca. You've accepted that you will never wear the pants in the marriage arrangement, that's step 1. you could tactically avoid Das Boot by telling her that you are writing a thank you card to her mother or shopping for a gift for her online. you should get a wider berth. a friend told me this works
.
blueicetwice Five stars to Brent on Google Map, for his suggestion, which lead
to this success !!
**there's an open source map in the repo.
- Edited
Lots of laughs, Brent!!! I'll leave Minty on the curb for the Phoenix Coyotes.
Our abode is on a sailboat, so the "winder berth" is not an option.