Before Green Day played “Longview” from their 1994 album Dookie during an exuberant headline set at the Hella Mega tour Friday, Billie Joe Armstrong asked the hyper-enthused Citizens Bank Park crowd if there were any old-school fans in the house.

Yes, of course there were. He followed with a second question. “How about middle school? That’s more like it.”

It is. Green Day is a starter band that sticks with you, a gateway drug into catchy chorus punk-rock that began pulling in young fans 30 years ago and is still at it, judging from the wide age range of the full house at the Phillies’ stadium in South Philadelphia.

And the band’s Ramones-derived three-chords and full-speed-ahead approach still packs plenty of pop. Songs of alienation and self-loathing — “Longview” is about, among other things, “when masturbation’s lost its fun” — perk up to embrace the moment.

The 21-song set was preceded by the utterly charming Green Day ritual of the crowd singing along to recordings of “Bohemian Rhapsody” and “Blitzkrieg Bop” before the band entered with “American Idiot,” the title cut to the 2004 album that established Armstrong as a rock-opera auteur.

“Holiday,” also from the American Idiot album, established the template. It’s a serious protest against the then-concurrent U.S. wars in Iraq and Afghanistan. But it plays out as a celebration.

“I beg to dream and differ from the hollow lies,” Armstrong sang, accompanied by bandmates Mike Dirnt on bass and Tré Cool on drums. “This is the dawning of the rest of our lives!”

That carpe diem theme ran through the band’s 90-minute performance, which was frequently punctuated with fireworks and featured the trio augmented by three auxiliary musicians. It played extremely well with an audience that was more than ready to rock.

The Hella Mega tour, which ran for 5½ hours and also featured Fall Out Boy, Weezer, and the ska-punk openers The Interrupters, was supposed to happen last summer but was postponed because of the COVID-19 shutdown.

But tickets originally went on sale in September 2019, so the fans who high-fived and toasted each other during “Still Breathing” and stood in astonishingly long merch lines — everybody wants a Green Day shirt — had been waiting almost two full years to see the show.

Armstrong acknowledged that yearning during the set, which didn’t feature a song from last year’s Father of All M— album but did include covers of Kiss’ “Rock and Roll All Nite” and Operation Ivy’s “Knowledge.” It concluded with the earnestly strummed ballad “Good Riddance (Time of Your Life),” which showcases the prom-theme/wedding-song side of Green Day that’s key to their enduring popularity.

“Put your phones down!” Armstrong implored the crowd early on. “We’ve been looking at our phones for a year and a half. Now we have each other. Now we can hug each other. Now we can kiss each other.”

Can we? In fact, one shirtless dude overcome with love for humanity did try to give me a big hug after “Bohemian Rhapsody.” But the concert was staged at a fraught moment when live music is moving forward despite fears of the delta variant of the coronavirus.

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Proof of vaccination or a negative COVID-19 test was not needed to enter Hella Mega. Instead, the show followed Philadelphia’s mask mandate protocols, in which masks are only required in the stadium’s indoor spaces. Most fans went maskless outdoors.

A vaccine or a test was to be required, however, at the Dead & Company show the very next night at the ballpark. And here’s a fun fact: Tré Cool took drum lessons from the Grateful Dead’s Mickey Hart. Green Day and the Dead are San Francisco Bay Area bands who march to the beat of different drummers, so to speak.

I missed The Interrupters, so my Mega night began with Weezer’s delightful hour-long set. Playing a Flying V guitar in trademark black glasses and sporting a pandemic mullet, Rivers Cuomo got nerdy with songs built on crunchy power chords that left plenty of space for audience participation. “All my favorite songs are slow and sad,” he sang. “I don’t know what’s wrong with me.”

Coming on in a rainstorm that began as Weezer closed with “Buddy Holly,” Fall Out Boy — back on tour after missing three shows due to a COVID-19 diagnosis — followed with an hour of aggressive emo-pop.

Flames shot out of Pete Wentz’s bass and singer Patrick Stump sang songs much denser and less immediately appealing — and with longer titles like “This Ain’t a Scene, It’s an Arms Race” and “My Songs Know What You Did in the Dark” — than those of the bands they were sandwiched between.