Thank you for the pointers Adam. The string did not match the file on disk because I neglected to open the file in binary mode. Commenting out the custom option coincidentally made everything work leading me down the rat hole but the real fix is to open in binary mode and then everything works.
I don't think this necessarily has anything to do with the custom option.
FileDescriptorSet is itself just a protocol buffer message, so parsing it
doesn't involve interpreting the meaning of its contents. It's just like
parsing any other proto, so if it's failing then either the descriptors
were
I am invoking protoc –descriptor_set_out on the .proto file with contents described below that include the definition of the custom option. I’m not sure what else you are suggesting I include. I attached the .proto file to clarify the reproduction steps.protoc –descriptor_set_out simple.proto Use
