Selena took to social media Wednesday to wish Francia happy birthday, posting what appears to be an old photo of them along with the caption ... "Happiest of birthdays to this special human beings. No matter where life takes us, I love you. ❤️ @franciaraisa."

It's a noteworthy post from Selena ... Francia recently revealed their relationship was broken ... so this could be a sign Selena wants to patch things up.

The outstanding issue ... Francia took offense to an interview where Selena said the only person she was close to in Hollywood was Taylor Swift.

Selena's answer didn't sit right with Francia, because the two former child actors go way back and she donated a kidney to Selena in 2017.

Francia unfollowed Selena after the interview and still does not follow her on IG ... so it will be interesting to see if the birthday post moves the needle.