Houston, the spacesuits don’t fit.

The first ever all-female spacewalk won’t be happening this week after all — because of an issue with spacesuit sizing, NASA announced on Monday.

The history-making excursion was set to happen Friday as astronauts Christina Koch and Anne McClain were scheduled to swap out the 3,000-pound batteries on the outside of the International Space Station.

But now, astronaut Nick Hague will take McClain’s place, the space agency said in a statement.

“It means the [all-female spacewalk] is at least not happening this Friday,” spokesperson Stephanie Schierholz told The Post Monday. “We anticipate it will happen at some point in the future.”

NASA said the switch-up has to do with what sizes of spacesuits are available on the ISS.

When McClain completed a successful spacewalk March 22, she realized that a suit with a “medium-size upper torso” fits her best, according to the statement.

That’s also the size suit that fits Koch best — but only one is available for Friday’s seven-hour spacewalk.

Meanwhile, two large suits and one of two extra-large suits are available, Schierholz said.

The original all-female crew was actually just a coincidence and not planned, Schierholz had previously said.

“It was kind of a cool coincidence,” she added on Monday. “But Anne is still the 13th woman and Christina the 14th.”

“[The all-female spacewalk] is likely to happen, just not this time. Our teams do best they can on upcoming crew assignments.”