External boot drive to repair internal drive?

Thanks.I was able to boot the Mac from an external drive which has Sierra .I then ran disk utility on the internal drive, ran the first aid successfully & then erased that drive completely.Now wondering what I should do next.Will I be able to install Catalina on the empty drive now?

Thanks.

Well I tried to install OS from the internet but I get this message saying ,'Recovery server cold not be found'.So now I went to a time machine backup & restoring it.When I tried Time machine previously before I got myself into all this drama, it failed.But now that the disk is cleaned up & repaired I trust it will go smooth.

Really appreciate your help on this.Customer service wasn't of much help & didn't offer these solutions like you did.

Thanks.

Thanks to your guidance, time machine worked this time & I restored it to April 2019 with Mojave to be on the safe side.Yes I repaired the internal drive & erased the drive.Since the recovery server was not located I thought the best thing would be to go for Time Machine backup.I may have to update some plugins & stuff .I see things are a bit slow now to start with & the spinning ball appears but hopefully it should all be settled.

I did not restore the most recent backup just to make sure I don't get any virus in, but will I be able to migrate certain programs such as the Library without having to go through a complete restore from scratch? Since I'm a musician using Logic X I had a lot of 3rd party plugins.

My intention was upgrading to Catalina & in the process I landed up in a mess.Glad I'm out of it.I am going to try downloading Catalina later on an external drive to see how things work.Most folks on the Logic forum don't seem to recommend Catalina though.

Hi Mr.William,

i needed your input on another issue I ran into.I was hoping to run Big Sur or Catalina on an external USB bootable drive & so went through the process & got it onto the drive.

I got Big Sur on an external bootable drive using the terminal...& everything went well

But when booting from the ext drive I see the language drop down menu screen & then everything freezes & I am unable to do anything from there. Nothing happens when I press enter or move the wireless mouse. I posted on a different thread but had no idea how to get in touch with you as Apple techs on chat simply did not have a clue & are of little help like before!

You may wonder why i am attempting the Catalina & Big Sur route! I purchased softwares on the Apple store with codes & when trying to register & install those codes it did not go through & was asking for me to upgrade to Catalina or Big Sur.If Apple could only get it registered i wont even go the uograde path for now.However upgrading has been so much of an issue now with these hurdles.I would really appreciate your input on what I should do. Thanks

Thanks.

Thanks a lot for responding.The imac is 2017 27” .This is what happens: The installer runs for about 5 mins & opens up on a blank screen with the language menu. But then the keyboard & mouse doesn’t function at that point. I have a feeling that something disables them . If it functions, I would hit enter to select the English language option & click on continue to proceed further.

External usb drive is 120 GB.I will try a different drive. The imac has about 75 gb free space.

Thank you.Right now the external bootable drive is running on Sierra. So any workarounds or ideas on what I should be doing?

I restarted the Mac without the bootable drive & I see a no entry sign (circle ).I guess there's nothing on the computer now.How do I install OS on this 'new' drive pls?