The New York City Opera has struck a sour note with its workers — so they filed a federal labor complaint yesterday.

The American Guild of Musical Artists claims that the opera unilaterally announced big changes — including leaving Lincoln Center — without mandated bargaining.

“They haven’t told us where they’re moving or how much work [employees] will have,” said AGMA official Alan Gordon.

Opera spokeswoman Maggie McKeon called the filing “without merit.”