I can almost guarantee when you redid your "loose" wire you connected it to the wrong thing. There's more to house wiring than matching up the colors.

I connected it to the same place as before when the light worked. I’m more concerned with why it sparks when I attach it to the metal box.

turn off the power, take off the cover and the screws holding the switch in place. Pull out the switch so we can see the wires and post a photo.

With such sparks the options are the switch has some hideous, rarely seen ground fault -OR- you didn't quite get it right.

We can all speculate - or we can get a photo...

Phoenix, AZ. House built in 1969. I matched the wiring from the old switch to the new. To your point this is the only ground wire that is not bare, but on the last switch it was hooked up this way. There is a bare wire inside the box that is attached to the metal casing.

Bruce you’re right. The old switch was a 3-way. Do I need to replace with a 3 way or can I use a 2 way and disregard the red wire?

Yep, It sure looks like you connected the red wire for a 3-way switch to the ground terminal on a single pole switch.

You cannot install a two way and disregard the red. That will not work right.

Just buy a three way switch and connect it properly.

Thanks guys! I purchased 3-way and life is good. Appreciate the help.

All I can say is, thank goodness for circuit breakers. And can you imagine what might have happened there if the circuit hadn't been properly grounded? Every metal box on the circuit could have become energized, along with every metallic appliance plugged into it with a 3-pin cord and plug. Someone might have been killed.

I wonder if in some ways homeowners weren't better off back in the early days of electricity in homes, when many of them were afraid of it and therefore left installation and repair to the pros.

The old cliche is that familiarity breeds contempt. I'd say it breeds carelessness.

This is a perfect example of why DIY is great in general, but, when it comes to something that can kill you, a little knowledge is a dangerous thing. I'm glad the OP solved the problem, but this is frightening. The problem with electrical work is when you don't know enough to know you don't know enough....

The thing that changed by the way was almost certainly that someone flipped the OTHER switch in this three way which now meant you were routing 120V to the ground through the mounting ears of the device. Thank heavens you had a properly grounded metal box, otherwise you might have killed a loved one rather than just tripping the breaker.

I used to recommend that beginners read Wiring Simplified because it had a chapter on basic electrical principles. The editions I've seen in recent years have dropped that chapter, so I no longer recommend it. I don't know what to suggest now.