I agree with Laurel, that's great advise In your case also, if baby is 9 months and gagging continuously on a majority of foods, I would get your child health nurse to check their palate and a speech pathologist to check their swallowing. Might be an underlying issue. If all is well, then continue trying like Laurel said!
My daughter was assessed and she has a smaller than average back of her mouth which makes it difficult for her to swallow. She's 15 months and is only just now eating meals. We still do some bottle feed top ups.
So before you try again I recommend watching a video on baby heimleich just in case! And also read up on the difference between gagging and choking in babies! And then try baby led weaning there is a great group on Facebook blwbb and an app called solid starts! I always recommend starting with foods you can easily mash between thumb and forefinger because baby can easily mash with gums!