survminer error

packages

#1

I am working on SEER cancer survial data and with the survminer package I get the error in the attached image. I could do the analysis with other survival related packages.
I have searched many web sites but could not identify the meaning of this error.
I would like to get your opinions on the possible cause of this error.

Best wishes

library(survminer)
ggsurvplot(km_fit)