No other driver supports updating an existing GridFS file. The reason given is that this is a very dangerous operation, because while the update is in progress the GridFS file is in an intermediate state and if any other process or thread tries to read the GridFS file during that time the results will be unpredictable.

This involves removing or changing the following methods:

MongoGridFS class:
remove AppendText method
rename Create methods to CreateNew (because Create FileMode is no longer supported)
rename CreateText methods to CreateTextNew (because Create FileMode is no longer supported)
Open methods won't support FileModes: Create, OpenOrCreate, Truncate or Append (only Open or CreateNew will be supported)

MongoGridFSFileInfo class:
remove AppendText method
rename Create methods to CreateNew (because Create FileMode is no longer supported)
rename CreateText methods to CreateTextNew (because Create FileMode is no longer supported)
Open methods won't support FileModes: Create, OpenOrCreate, Truncate or Append (only Open or CreateNew will be supported)

This change is scheduled for version 1.3 to provide sufficient time for comments.