sbt package报错：a bytes-like object is required, not 'str'

Traceback (most recent call last):
  File "C:UsersUserAppDataLocalTempprotocbridge7256923893821185625.py", line 6, in <module>
    s.sendall(content)
TypeError: a bytes-like object is required, not 'str'
--scala_out: protoc-gen-scala: Plugin failed with status code 1.
[error] java.lang.RuntimeException: protoc returned exit code: 1
[error]         at scala.sys.package$.error(package.scala:26)
[error]         at sbtprotoc.ProtocPlugin$.compile(ProtocPlugin.scala:139)
[error]         at sbtprotoc.ProtocPlugin$.compileProto$1(ProtocPlugin.scala:180)
[error]         at sbtprotoc.ProtocPlugin$.$anonfun$sourceGeneratorTask$4(ProtocPlugin.scala:184)
[error]         at sbt.util.FileFunction$.$anonfun$cached$1(FileFunction.scala:73)
[error]         at sbt.util.FileFunction$.$anonfun$cached$4(FileFunction.scala:147)
[error]         at sbt.util.Difference.apply(Tracked.scala:313)
[error]         at sbt.util.Difference.apply(Tracked.scala:293)
[error]         at sbt.util.FileFunction$.$anonfun$cached$3(FileFunction.scala:143)
[error]         at sbt.util.Difference.apply(Tracked.scala:313)
[error]         at sbt.util.Difference.apply(Tracked.scala:288)
[error]         at sbt.util.FileFunction$.$anonfun$cached$2(FileFunction.scala:142)
[error]         at sbtprotoc.ProtocPlugin$.$anonfun$sourceGeneratorTask$1(ProtocPlugin.scala:190)
[error]         at scala.Function1.$anonfun$compose$1(Function1.scala:44)
[error]         at sbt.internal.util.$tilde$greater.$anonfun$$u2219$1(TypeFunctions.scala:40)
[error]         at sbt.std.Transform$$anon$4.work(System.scala:67)
[error]         at sbt.Execute.$anonfun$submit$2(Execute.scala:269)
[error]         at sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:16)
[error]         at sbt.Execute.work(Execute.scala:278)
[error]         at sbt.Execute.$anonfun$submit$1(Execute.scala:269)
[error]         at sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:178)
[error]         at sbt.CompletionService$$anon$2.call(CompletionService.scala:37)
[error]         at java.util.concurrent.FutureTask.run(FutureTask.java:266)
[error]         at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
[error]         at java.util.concurrent.FutureTask.run(FutureTask.java:266)
[error]         at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
[error]         at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
[error]         at java.lang.Thread.run(Thread.java:748)
[error] (Compile / protocGenerate) protoc returned exit code: 1
[error] Total time: 4 s, completed 2020-1-13 9:42:52

搜索了一下，根据https://github.com/scalapb/ScalaPB/issues/268的讨论，可能是安装的python版本问题，非2.x版本可能导致sbt package时出现上面的错误。安装python 2.7后问题解决。