Sorry, but your current information doesn't help to solve your problem. Not
having explicit base-learners is not the cause of your problem, especially
as for glmboost() there are no explicit base-learners. You should definitely
provide a minimal example that helps to reproduce your error/problem.
For me, everything works as intended:
## load mboost
library(mboost)
## set up model (in analogy to ?glmboost)
cars.gb <- glmboost(dist ~ speed, data = cars,
+ control = boost_control(mstop = 400))
## without new data
p1 <- predict(cars.gb)
head(p1)
Hard to debug given we neither have the formula nor the data.
All I can give is that the data is in the form y, x1, x2, x3,... and the
formula is y ~ x1+x2+x3+...
Maybe it's because I'm not explicitly specifying the base learners.