This error occurs because MigrationWiz failed to gather the list of all the folders from Google Drive within the allocated time. By default, MigrationWiz allows one (1) hour to initialize the migration but if using DocumentBrowsingMode=Moderate or if there is a very large number of folders, this can take much longer.
The best solution is to increase the timeout by using the Advanced Support Option InitializationTimeout. This value is in hours, up to a maximum of 100 hours. Values above 100 are in milliseconds. For example:
InitializationTimeout=2will increase the timeout to 2 hours.
InitializationTimeout=4will increase the timeout to 4 hours.
InitializationTimeout=6will increase the timeout to 6 hours.
InitializationTimeout=8will increase the timeout to 8 hours.
InitializationTimeout=7200000will increase the timeout to 2 hours.
InitializationTimeout=14400000will increase the timeout to 4 hours.
InitializationTimeout=21600000will increase the timeout to 6 hours.
InitializationTimeout=28800000will increase the timeout to 8 hours.
Review How do I add support options to a project or to a single item? to learn how to set an Advanced Support Option for your project or item(s).