On Mac With plugin and library 0.4.8 - on "import krpc" receive that error, along with the following output:

Python 3.6.5 (default, May 15 2018, 22:12:43)
[GCC 4.2.1 Compatible Apple LLVM 9.0.0 (clang-900.0.38)] on darwin
Type "help", "copyright", "credits" or "license" for more information.

import krpc
Traceback (most recent call last):
File "", line 1, in
File "/usr/local/lib/python3.6/site-packages/krpc/init.py", line 1, in
from krpc.connection import Connection
File "/usr/local/lib/python3.6/site-packages/krpc/connection.py", line 3, in
from krpc.encoder import Encoder
File "/usr/local/lib/python3.6/site-packages/krpc/encoder.py", line 8, in
import krpc.schema.KRPC_pb2 as KRPC
File "/usr/local/lib/python3.6/site-packages/krpc/schema/KRPC_pb2.py", line 22, in
serialized_pb=_b('\n\x13protobuf/krpc.proto\x12\x0bkrpc.schema"\x93\x01\n\x11\x43onnectionRequest\x12\x31\n\x04type\x18\x01 \x01(\x0e\x32#.krpc.schema.ConnectionRequest.Type\x12\x13\n\x0b\x63lient_name\x18\x02 \x01(\t\x12\x19\n\x11\x63lient_identifier\x18\x03 \x01(\x0c"\x1b\n\x04Type\x12\x07\n\x03RPC\x10\x00\x12\n\n\x06STREAM\x10\x01"\xbe\x01\n\x12\x43onnectionResponse\x12\x36\n\x06status\x18\x01 \x01(\x0e\x32&.krpc.schema.ConnectionResponse.Status\x12\x0f\n\x07message\x18\x02 \x01(\t\x12\x19\n\x11\x63lient_identifier\x18\x03 \x01(\x0c"D\n\x06Status\x12\x06\n\x02OK\x10\x00\x12\x15\n\x11MALFORMED_MESSAGE\x10\x01\x12\x0b\n\x07TIMEOUT\x10\x02\x12\x0e\n\nWRONG_TYPE\x10\x03"4\n\x07Request\x12)\n\x05\x63\x61lls\x18\x01 \x03(\x0b\x32\x1a.krpc.schema.ProcedureCall"\x87\x01\n\rProcedureCall\x12\x0f\n\x07service\x18\x01 \x01(\t\x12\x11\n\tprocedure\x18\x02 \x01(\t\x12\x12\n\nservice_id\x18\x04 \x01(\r\x12\x14\n\x0cprocedure_id\x18\x05 \x01(\r\x12(\n\targuments\x18\x03 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TypeError: new() got an unexpected keyword argument 'serialized_options'

Reverting to 0.4.7 and it works fine.

Probably a protobuf compatibility issue. kRPC v0.4.8 was built against protobuf 3.6.1. kRPC v0.4.7 was built against protobuf 3.5.1. Maybe try upgrading your protobuf and see if that fixes the issue?

This happens to me too.
In my case protobuf:3.5.2.post1 was installed and pip install -U protobuf just solved the issue.

How about to update setup.py to specify required protobuf version a bit more detail?
I made the PR #510.

The change in protobuf seems to be introduced in 3.6.0 at this commit, I believe protobuf>=3.6 would be detailed enough.

i had the same problem, but after updating protobuf to 3.6.1 there was a new error on importing:

File "C:/Users/Flo/Python/ksp/testhopper.py", line 8, in
import krpc

File "C:\ProgramData\Anaconda3\lib\site-packages\krpc_init_.py", line 1, in
from krpc.connection import Connection

File "C:\ProgramData\Anaconda3\lib\site-packages\krpc\connection.py", line 3, in
from krpc.encoder import Encoder

File "C:\ProgramData\Anaconda3\lib\site-packages\krpc\encoder.py", line 8, in
import krpc.schema.KRPC_pb2 as KRPC

File "C:\ProgramData\Anaconda3\lib\site-packages\krpc\schema\KRPC_pb2.py", line 22, in
serialized_pb=_b('\n\x13protobuf/krpc.proto\x12\x0bkrpc.schema"\x93\x01\n\x11\x43onnectionRequest\x12\x31\n\x04type\x18\x01 \x01(\x0e\x32#.krpc.schema.ConnectionRequest.Type\x12\x13\n\x0b\x63lient_name\x18\x02 \x01(\t\x12\x19\n\x11\x63lient_identifier\x18\x03 \x01(\x0c"\x1b\n\x04Type\x12\x07\n\x03RPC\x10\x00\x12\n\n\x06STREAM\x10\x01"\xbe\x01\n\x12\x43onnectionResponse\x12\x36\n\x06status\x18\x01 \x01(\x0e\x32&.krpc.schema.ConnectionResponse.Status\x12\x0f\n\x07message\x18\x02 \x01(\t\x12\x19\n\x11\x63lient_identifier\x18\x03 \x01(\x0c"D\n\x06Status\x12\x06\n\x02OK\x10\x00\x12\x15\n\x11MALFORMED_MESSAGE\x10\x01\x12\x0b\n\x07TIMEOUT\x10\x02\x12\x0e\n\nWRONG_TYPE\x10\x03"4\n\x07Request\x12)\n\x05\x63\x61lls\x18\x01 \x03(\x0b\x32\x1a.krpc.schema.ProcedureCall"\x87\x01\n\rProcedureCall\x12\x0f\n\x07service\x18\x01 \x01(\t\x12\x11\n\tprocedure\x18\x02 \x01(\t\x12\x12\n\nservice_id\x18\x04 \x01(\r\x12\x14\n\x0cprocedure_id\x18\x05 \x01(\r\x12(\n\targuments\x18\x03 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File "C:\ProgramData\Anaconda3\lib\site-packages\google\protobuf\descriptor.py", line 908, in init
_message.default_pool.AddSerializedFile(self.serialized_pb)

NameError: name '_message' is not defined

UPDATE: updating to protobuf 3.7.0 fixed my error

Closing as should be fixed by #510