I have a General (under honorable conditions) discharge for smoking cannabis can I upgrade it? Is it worth it?

The "Is it worth it" depends on you. From the point of view of impact of VA services, Veterans who receive general discharges under honorable conditions are entitled to all VA benefits, with the exception of GI Bill education benefits.

You said that you were discharged back in 2001, so you wouldn't be eligible for the Post-9/11 GI Bill. However, if you had paid into the Montgomery GI Bill while on active duty (that $100 a month thing) and didn't use it up, then that would be something you would get back if your discharge was upgraded.

However, if you aren't eligible for the GI Bill, then frankly I can't think of any impact to you other than having a DD215 saying it was upgraded. You were still discharged under Honorable conditions but had a blemish or two on the discharge. That's it. If the blemishes bother you, you can go through the route of getting it upgraded.

Frankly, you'll have an uphill battle, UNLESS can show that you had a single isolated incident or that you were suffering from PTSD (there are a lot of exceptions that could apply if that was the case). If either of these apply, then contact a VSO and get their assistance in filing for an upgrade.

You're not going to upgrade it unless you can prove it was erroneous.

You can try but I don't know if it will pan out. Cannabis is still a schedule 1 drug and is still illegal federally.

https://www.military.com/daily-news/2022/10/07/bidens-marijuana-pardons-dont-apply-service-members.html