Random Forest in R with only character variables
You can check the class of the class(df$dependent). You are expecting it to be numeric.

To convert multiple columns to factors, you can do something like this

factor_cols &lt;- c("col_1","col_7"), 
df[factor_cols] &lt;- lapply(df[factor_cols], as.factor)


If you keep the customer id,  then you will have a problem when applying your model to a new customer.