When predictor rasters are in a geodatabase, Predict GLM / Predict GAM / Predict Tree fail with RPy_RException: Error in .local(.Object, ...) : `C:\...' does not exist in the file system, and is not recognised as a supported dataset name.

[jjr8]

The problem is that the rgdal R package cannot read rasters from geodatabases. MGET should temporarily copy the predictor rasters out of geodatabases before calling the R code for the prediction.