(DatabaseError) error with no message from the libpq

[Christian Barra]

Hi guys, sometimes I get this error:

Exception on /auth/login [POST] Traceback (most recent call last): File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/engine/base.py", line 951, in _execute_context context) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/engine/default.py", line 436, in do_execute cursor.execute(statement, parameters) File "/usr/local/lib/python3.4/dist-packages/newrelic-2.40.0.34/newrelic/hooks/database_dbapi2.py", line 22, in execute args, kwargs) psycopg2.DatabaseError: error with no message from the libpq The above exception was the direct cause of the following exception: Traceback (most recent call last): File "/usr/local/lib/python3.4/dist-packages/flask/app.py", line 1817, in wsgi_app response = self.full_dispatch_request() File "/usr/local/lib/python3.4/dist-packages/flask/app.py", line 1477, in full_dispatch_request rv = self.handle_user_exception(e) File "/usr/local/lib/python3.4/dist-packages/newrelic-2.40.0.34/newrelic/hooks/framework_flask.py", line 98, in nr_wrapper_Flask_handle_exception return wrapped(args, kwargs) File "/usr/local/lib/python3.4/dist-packages/flask/app.py", line 1381, in handle_user_exception reraise(exc_type, exc_value, tb) File "/usr/local/lib/python3.4/dist-packages/flask/compat.py", line 33, in reraise raise value File "/usr/local/lib/python3.4/dist-packages/flask/app.py", line 1475, in full_dispatch_request rv = self.dispatch_request() File "/usr/local/lib/python3.4/dist-packages/flask/app.py", line 1461, in dispatch_request return self.view_functionsrule.endpoint File "/usr/local/lib/python3.4/dist-packages/newrelic-2.40.0.34/newrelic/hooks/framework_flask.py", line 40, in _nr_wrapper_handler return wrapped(*args, kwargs) File "./main/views.py", line 63, in auth_login user = User.query.filter_by(username=username).first() File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/orm/query.py", line 2367, in first ret = list(self[0:1]) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/orm/query.py", line 2228, in getitem return list(res) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/orm/query.py", line 2438, in iter return self._execute_and_instances(context) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/orm/query.py", line 2453, in _execute_and_instances result = conn.execute(querycontext.statement, self._params) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/engine/base.py", line 729, in execute return meth(self, multiparams, params) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/sql/elements.py", line 322, in _execute_on_connection return connection._execute_clauseelement(self, multiparams, params) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/engine/base.py", line 826, in _execute_clauseelement compiled_sql, distilled_params File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/engine/base.py", line 958, in _execute_context context) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/engine/base.py", line 1159, in _handle_dbapi_exception exc_info File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/util/compat.py", line 188, in raise_from_cause reraise(type(exception), exception, tb=exc_tb, cause=exc_value) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/util/compat.py", line 181, in reraise raise value.with_traceback(tb) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/engine/base.py", line 951, in _execute_context context) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/engine/default.py", line 436, in do_execute cursor.execute(statement, parameters) File "/usr/local/lib/python3.4/dist-packages/newrelic-2.40.0.34/newrelic/hooks/database_dbapi2.py", line 22, in execute args, *kwargs)

sqlalchemy.exc.DatabaseError: (DatabaseError) error with no message from the libpq 'SELECT users.id AS users_id, users.username AS users_username, users.first_name AS users_first_name, users.last_name AS users_last_name, users.password AS users_password, users.status AS users_status, users.is_staff AS users_is_staff, users.user_plan AS users_user_plan, users.last_login AS users_last_login, users.date_joined AS users_date_joined, users.reset_password_token AS users_reset_password_token \nFROM users \nWHERE users.username = %(username_1)s \n LIMIT %(param_1)s' {'param_1': 1, 'username_1': '[e-mail]'}

[Christian Barra]

And this is the line n. 63 of views.py

user = User.query.filter_by(username=username).first()

[Mike Bayer]

definitely nothing on sqlalchemy's side, have not seen this error with psycopg2 either, however oddly psycopg2 isn't in the stack trace here. newrelic/hooks/database_dbapi2.py seems the cause of the issue so raise this with newrelic support.

[Christian Barra]

Hi Mike, I have removed New Relic from my stack. But it comes back !

Traceback (most recent call last): File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/engine/base.py", line 951, in _execute_context context) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/engine/default.py", line 436, in do_execute cursor.execute(statement, parameters) psycopg2.DatabaseError: error with no message from the libpq The above exception was the direct cause of the following exception: Traceback (most recent call last): File "/usr/local/lib/python3.4/dist-packages/flask/app.py", line 1817, in wsgi_app response = self.full_dispatch_request() File "/usr/local/lib/python3.4/dist-packages/flask/app.py", line 1477, in full_dispatch_request rv = self.handle_user_exception(e) File "/usr/local/lib/python3.4/dist-packages/flask/app.py", line 1381, in handle_user_exception reraise(exc_type, exc_value, tb) File "/usr/local/lib/python3.4/dist-packages/flask/_compat.py", line 33, in reraise raise value File "/usr/local/lib/python3.4/dist-packages/flask/app.py", line 1475, in full_dispatch_request rv = self.dispatch_request() File "/usr/local/lib/python3.4/dist-packages/flask/app.py", line 1461, in dispatch_request return self.view_functionsrule.endpoint File "./main/views.py", line 63, in auth_login user = User.query.filter_by(username=username).first() File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/orm/query.py", line 2367, in first ret = list(self[0:1]) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/orm/query.py", line 2228, in getitem return list(res) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/orm/query.py", line 2438, in iter return self._execute_and_instances(context) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/orm/query.py", line 2453, in _execute_and_instances result = conn.execute(querycontext.statement, self._params) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/engine/base.py", line 729, in execute return meth(self, multiparams, params) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/sql/elements.py", line 322, in _execute_on_connection return connection._execute_clauseelement(self, multiparams, params) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/engine/base.py", line 826, in _execute_clauseelement compiled_sql, distilled_params File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/engine/base.py", line 958, in _execute_context context) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/engine/base.py", line 1159, in _handle_dbapi_exception exc_info File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/util/compat.py", line 188, in raise_from_cause reraise(type(exception), exception, tb=exc_tb, cause=exc_value) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/util/compat.py", line 181, in reraise raise value.with_traceback(tb) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/engine/base.py", line 951, in _execute_context context) File "/usr/local/lib/python3.4/dist-packages/sqlalchemy/engine/default.py", line 436, in do_execute cursor.execute(statement, parameters) sqlalchemy.exc.DatabaseError: (DatabaseError) error with no message from the libpq 'SELECT users.id AS users_id, users.username AS users_username, users.first_name AS users_first_name, users.last_name AS users_last_name, users.password AS users_password, users.status AS users_status, users.is_staff AS users_is_staff, users.user_plan AS users_user_plan, users.last_login AS users_last_login, users.date_joined AS users_date_joined, users.reset_password_token AS users_reset_password_token \nFROM users \nWHERE users.username = %(username_1)s \n LIMIT %(param_1)s' {'username_1': '[e-mail]', 'param_1': 1}

[Mike Bayer]

christian -

this is still nothing to do with sqlalchemy. the query is very average and the error message here is not generated by sqlalchemy, it is from your DBAPI psycopg2. there is also no information here of any kind to illustrate any potential cause of this issue so even if it were sqlalchemy's problem there'd be no way for us to do anything here.

your next stop is the psycopg2 mailing list. since this is python 3.4 maybe this is some issue there specific to their python 3.4 version since Ive never seen this message before. they should have a better clue what might be causing this problem.

the next post over here must include a test script, which is a single file example I can run that will illustrate this message. otherwise there's not any information to illustrate what causes this except for whatever psycopg2 devs might know. thanks!

[Christian Barra]

Thanks Mike.