First and second stages performed normally, but the third stage did not:

https://x.com/isro/status/1923907158133047606

Today 101st launch was attempted, PSLV-C61 performance was normal till 2nd stage. Due to an observation in 3rd stage, the mission could not be accomplished.

https://bsky.app/profile/planet4589.bsky.social/post/3lpfxttzqic25

LAUNCH at 0029 UTC May 18 and FAILURE of ISRO's PSLV-61 carrying the EOS-09 radar satellite. Third stage failed, fourth stage and satellite did not reach orbit.

https://bsky.app/profile/nasaspaceflight.com/post/3lpfvtaew322e

On ISRO’s live broadcast, we heard “We are seeing an observation.” It appears there was a third-stage mishap which will cause EOS-09 to not make orbit. Image here shows a telemetry deviation at approx T+365 seconds.

https://x.com/dpoddolphinpro/status/1923905851611332868

LAUNCH FAILURE: EOS-09 will not be making it to orbit due to a 3rd stage mishap. We can see a huge telemetry deviation approximately 365 seconds into flight. @ISRO: "We are seeing an observation".

This marks the first failure of a PSLV-family rocket since 2017, and the third total-failure since debut in 1993.