Issue connecting to MySQL database after installing Pychron for data reduction

[cmmercer]

I ran into this error message when trying to set up Pychron for data reduction. I used the Enthought Deployment Manager (EDM) shell to install Pychron dependencies with edm install <package list>, but when trying to test connecting to a MySQL database the following error was logged:

File "/Users/<username>/Documents/Pychron/pychron/database/core/database_adapter.py", line 542, in _test_db_connection getattr(self, self.test_func)(reraise=True)
File "/Users/<username>/Documents/Pychron/pychron/dvc/dvc_database.py", line 290, in get_versions return [r.version for r in q.all()]
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/orm/query.py", line 3341, in all return list(self)
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/orm/query.py", line 3503, in __iter__ return self._execute_and_instances(context)
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/orm/query.py", line 3525, in _execute_and_instances querycontext, self._connection_from_session, close_with_result=True
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/orm/query.py", line 3540, in _get_bind_args mapper=self._bind_mapper(), clause=querycontext.statement, **kw
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/orm/query.py", line 3518, in _connection_from_session conn = self.session.connection(**kw)
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/orm/session.py", line 1141, in connection execution_options=execution_options,
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/orm/session.py", line 1147, in _connection_for_bind engine, execution_options
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/orm/session.py", line 433, in _connection_for_bind conn = bind._contextual_connect()
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 2305, in _contextual_connect self._wrap_pool_connect(self.pool.connect, None),
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 2339, in _wrap_pool_connect return fn()
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/pool/base.py", line 364, in connect return _ConnectionFairy._checkout(self)
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/pool/base.py", line 778, in _checkout fairy = _ConnectionRecord.checkout(pool)
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/pool/base.py", line 495, in checkout rec = pool._do_get()
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/pool/impl.py", line 140, in _do_get self._dec_overflow()
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/util/langhelpers.py", line 69, in __exit__ exc_value, with_traceback=exc_tb,
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/util/compat.py", line 178, in raise_ raise exception
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/pool/impl.py", line 137, in _do_get return self._create_connection()
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/pool/base.py", line 309, in _create_connection return _ConnectionRecord(self)
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/pool/base.py", line 440, in __init__ self.__connect(first_connect_check=True)
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/pool/base.py", line 661, in __connect pool.logger.debug("Error on connect(): %s", e)
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/util/langhelpers.py", line 69, in __exit__ exc_value, with_traceback=exc_tb,
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/util/compat.py", line 178, in raise_ raise exception
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/pool/base.py", line 656, in __connect connection = pool._invoke_creator(self)
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/engine/strategies.py", line 114, in connect return dialect.connect(*cargs, **cparams)
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/sqlalchemy/engine/default.py", line 493, in connect return self.dbapi.connect(*cargs, **cparams)
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/pymysql/__init__.py", line 90, in Connect return Connection(*args, **kwargs)
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/pymysql/connections.py", line 688, in __init__ self.connect()
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/pymysql/connections.py", line 905, in connect self._get_server_information()
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/pymysql/connections.py", line 1231, in _get_server_information self.server_charset = charset_by_id(lang).name
File "/Users/<username>/.edm/envs/pychron/lib/python3.6/site-packages/pymysql/charset.py", line 38, in by_id return self._by_id[id]
KeyError: 255

[cmmercer]

Jake pointed out that the issue was with the pymysql package. The solution is to (in an edm shell -e pychron session) remove the version installed with edm remove pymysql, then reinstall with pip install pymysql. Connecting to the MySQL database worked after that!

[jirhiker]

A relevant stack exchange.
Please NOTE do not follow the suggested answer on stack exchange. Ive only added it here for context.

As pointed out by @cmmercer the solution is to install using pip
pip install pymysql

https://stackoverflow.com/questions/45368336/error-keyerror-255-when-executing-pymysql-connect