I'm curious. While the lessons present a number of ways to wish someone a happy birthday, "frohe Geburtstag" is not among them. That was what we were taught decades ago in my high school & college German classes. Is that outdated? Regional? Only something you see in writing, not spoken? Overly formal? Slang?
Frohe Geburtstag
RobertD50
June 16, 2021
Julia-Rocket-German-Tutor
June 21, 2021
Guten Tag RobertD50!
The most common phrases for wishing someone a happy birthday are “Alles Gute zum Geburtstag!" and “Herzlichen Glückwunsch (zum Geburtstag)!” You could say “Frohes Geburtstagsfest!” - “Happy birthday party!”, however this would be less common.
For festive occasions such as easter and christmas it is more common to use “frohe” as in “Frohe Ostern!” - “Happy Easter!" and “Frohe Weihnachten!”- “Merry Christmas!"
Hope this helps!
Viele Grüße,
Julia