If she's your girlfriend, shouldn't you know she has anxiety and panic attacks? Sorry, that just seems like something you should've known, OP. I've known for ages that my girlfriend hates having attention drawn to her and would get very anxious in that sort of situation, so while your intentions were good... Dude, you messed up and obviously weren't paying attention/don't know your girlfriend that well. Tl;dr - pay attention, and YDI.

I'm sorry OP. It was just unfortunate as you can't really predict panic attacks. But I do want to commend you on the gesture as it sounds like you are a real gentleman.

You probably should've known how bad her anxiety is...that would be a pretty panic inducing thing for someone who has it

If something like that gave her an anxiety attack, I assume she has anxiety attacks pretty often, so shouldn't that be something you're aware of?

Hope she's all right. Happy birthday to her, hope the rest of the night went well, as planned.

I'm sorry OP. I would have reacted the same as her, however I am saying it is her fault for not warning you. My fiance knows quite well that I would not enjoy it if he did something like that, so if he did it I would be clicking the You Deserve It button. But it seems from your post that you had no idea and she obviously should have forewarned you. I've been living with anxiety including social anxiety along with it for so long that I already know to warn people.

who goes to an upscale restaurant and tries to have someone sing happy birthday? This ain't Chucky Cheese

Although I have really bad anxiety issues, I let my mom tell the staff it was my birthday so I could get free dessert, I figured its only about 30 seconds of singing that I have to awkwardly get through.... it was definitely worth it

I feel like OP should have known that this would happen if he's at a stage in the relationship where he's taking her out to really nice restaurants for her birthday

I wouldn't say it's your fault at all, you were just being nice and it's a good gesture. But if you know she is anxiety prone, that's different