Attributeerror: '_dofnparam' Object Has No Attribute 'start' [while Running 'write To Gcs-ptransform-146']

When I run Beam program i'm getting below error. 2021-05-20T17:04:42.166994441ZError message from worker: generic::unknown: Traceback (most recent call last): File 'apache_bea

Solution 1:

In your WriteToGCS DoFn, you declared in the process method that the DoFn will take arg custom_options and output_path, however the they do not have default values and it seems the parameter translation will map the WindowParam onto the wrong arg.

you'll need to remove the unused parameters from the process method to make the DoFn parameter translation correct, additional parameters can be passed and retrieved from **kwargs in process fn.