Axl Rose -- Faceplants HARD at Guns N' Roses Concert

Here's some video that'll make Slash laugh ... his former bandmate Axl Rose getting a face full of stage after tripping and going down HARD at a concert in France.

Rose was trying to run on stage to belt out "Sweet Child o' Mine" on Saturday ... when he was confronted by a couple of unforgiving steps ... and lost.

Rose ate it ... face first ... but recovered like a pro and managed to get out the first words of the song right on cue.