ValueError: Number of features of the model must match the input

I am using random forest model to predict the sales quantity.
I have listed all parts in a row based while the quantity is in a monlthy based (each column represent a month)
During splitting the data in to train and test:
the training data will have less columns than the test set. meaning that I added one month to the test data.
when i run the model, an error is rasied :
ValueError: Number of features of the model must match the input. Model n_features is 22 and input n_features is 23.

Could you please help me on how to tackle this problem.

your help is really appreciated,
thanks in Advanced