(NewsNation) — Hype is growing for Taylor Swift’s next album, “The Tortured Poet’s Department.”

Swifties, as her fans are known, are trying to decipher a QR code that appeared in Chicago that may hold a clue about the new album, but everyone has a different theory.

The mural was added to a Chicago building Monday located at the intersection of Grand Avenue and Dearborn Street in the River North neighborhood.

The code appears to be composed of the letters “T-T-P-D” and the number 13 — a reference to the new album and Swift’s favorite number.

After scanning the code, the screen changes to a 13-second YouTube short on Swift’s official channel. The message, in typewriter font, reads: “Error 321,” along with a faded “13.”

The “error message” is intentional for Swifties, with more details expected on the album release date. Swift is known for her cryptic messages and Easter eggs ahead of her album releases.

“The Tortured Poets Department” debuts at midnight Friday.

NewsNation affiliate WGN contributed to this report.