Legendary rocker and AFI frontman Davey Havok FULLY supports a cover band taking over the upcoming Van Halen tour -- after the original band pulled out -- but he tells TMZ, there's a catch.

As we reported, Van Halen canceled its upcoming tour claiming the band's too tuckered out for a demanding string of live performances -- so a popular cover band called the Van Halen Army stepped forward, offering to fill in.

Davey says letting the cover band take the reigns is a great idea -- but only if fans aren't duped into thinking they're getting the real thing.

Davey adds, "That would be terribly upsetting."

A Van Halen cover band says that if the real Van Halen is too "burnt out" and too old to finish their postponed tour dates ... they are more than happy to take over.

Van Halen (the real one) cancelled the remainder of their 2012 tour on Friday, saying they needed to "re-charge their engines." They will be offering refunds for all the disappointed fans.

Joe -- who plays guitar in the Van Halen Army, a popular VH tribute band -- tells TMZ, "They have an obligation to fulfill ... somebody signs up to do the job they should complete it. Concerts these days cost a lot of money, they can't let the fans down ... they need to fulfill their end of the deal."

Joe also says, "We could easily do it -- our singer sounds exactly like David Lee Roth!"

Yeah, totally the same thing.

Even rockstars can get tired ... and TMZ has learned that's exactly why Van Halen decided to postpone 31 upcoming concert dates.

Sources close to the band tell us ... the guys felt like the current schedule was "too much, too fast" ... and they were "losing their focus."

One source tells us, "They're simply burned out" ... adding, "They want to make sure their concerts are not a routine ... they want every performance to be special."

We're told the guys want to take some time to "re-charge their engines" ... so they can rock all 31 cities the way Van Halen fans expect to be rocked.

As for rumors that Eddie Van Halen and David Lee Roth are feuding ... we're told "It's total B.S."

Former Van Halen front man Sammy Hagar has officially spaced out -- in fact, the guy actually claims he was abducted by real-life aliens several decades ago ... in Fontana ... and they had their way with his brain.


Hagar tells MTV, “It was real. They were plugged into me. It was a download situation … or, they uploaded something from my brain, like an experiment ... They were tapped into my brain and the knowledge was transferred back and forth."

Hagar insists the whole thing went down in Fontana, CA -- home to a NASCAR track.

According to the ex-rock star, it wasn’t his first extra-terrestrial experience either -- claiming he saw his first UFO when he was just four years old, hovering over a field near his home.

And just so we're clear, this isn't a joke -- Sammy insists, "That happened. That friggin’ happened."

Sources tell TMZ the Van Halen tour has just been canceled!

We're told arrangements are being made right now to cancel hotel stays for the tour -- which was scheduled to continue through April 19th. Sources tell us the reason for the cancellation is Eddie -- that he is having "issues."

The last three shows had already been canceled. There have been reports that Eddie was out of it during concerts -- and video of recent performances in which his guitar playing was atrocious.

Reps could not be reached for comment.