RuntimeError: Java gateway process exited before sending its port number

Question

When I initiate pyspark on pycharm / jupyter notebook, I just keep getting this error:

RuntimeError: Java gateway process exited before sending its port number

I did the following:

1. pip installed pyspark,
2. installed java 8, added environment variables,
3. tested java on cmd, input java, java -version, javac, all okay
4. in my code, I added os.environ['JAVA_HOME'] = 'D:\java', not working
5. added os.environ['PYSPARK_SUBMIT_ARGS'] = "--master local" not working

Pretty sure java 8 was set properly, however just kept getting this error.

please help