I'm just going through our error logs and came across this... I figure it might be helpful:
[25-Nov-2015 19:10:21 Australia/Sydney] [2015-11-25 19:10:21] EXCEPTION: (AphrontQueryException) #1048: Column 'content' cannot be null at [<phutil>/src/aphront/storage/connection/mysql/AphrontBaseMySQLDatabaseConnection.php:312] [25-Nov-2015 19:10:21 Australia/Sydney] arcanist(head=master, ref.master=72d9013d29dc), phabricator(head=master, ref.master=2047483cc046, custom=1), phlab(head=master, ref.master=cd07327495c5), phutil(head=master, ref.master=5538909d6468) [25-Nov-2015 19:10:21 Australia/Sydney] #0 <#2> AphrontBaseMySQLDatabaseConnection::throwQueryCodeException(integer, string) called at [<phutil>/src/aphront/storage/connection/mysql/AphrontBaseMySQLDatabaseConnection.php:275] [25-Nov-2015 19:10:21 Australia/Sydney] #1 <#2> AphrontBaseMySQLDatabaseConnection::throwQueryException(mysqli) called at [<phutil>/src/aphront/storage/connection/mysql/AphrontBaseMySQLDatabaseConnection.php:181] [25-Nov-2015 19:10:21 Australia/Sydney] #2 <#2> AphrontBaseMySQLDatabaseConnection::executeRawQuery(string) called at [<phutil>/src/xsprintf/queryfx.php:6] [25-Nov-2015 19:10:21 Australia/Sydney] #3 <#2> queryfx(AphrontMySQLiDatabaseConnection, string, string, string, array, string) [25-Nov-2015 19:10:21 Australia/Sydney] #4 <#2> call_user_func_array(string, array) called at [<phutil>/src/aphront/storage/connection/AphrontDatabaseConnection.php:28] [25-Nov-2015 19:10:21 Australia/Sydney] #5 <#2> AphrontDatabaseConnection::query(string, string, string, array, string) called at [<phabricator>/src/infrastructure/storage/lisk/LiskDAO.php:1261] [25-Nov-2015 19:10:21 Australia/Sydney] #6 <#2> LiskDAO::insertRecordIntoDatabase(string) called at [<phabricator>/src/infrastructure/storage/lisk/LiskDAO.php:1106] [25-Nov-2015 19:10:21 Australia/Sydney] #7 <#2> LiskDAO::insert() called at [<phabricator>/src/infrastructure/storage/lisk/LiskDAO.php:1075] [25-Nov-2015 19:10:21 Australia/Sydney] #8 <#2> LiskDAO::save() called at [<phabricator>/src/applications/transactions/editor/PhabricatorApplicationTransactionCommentEditor.php:65] [25-Nov-2015 19:10:21 Australia/Sydney] #9 <#2> PhabricatorApplicationTransactionCommentEditor::applyEdit(PhabricatorPasteTransaction, PhabricatorPasteTransactionComment) called at [<phabricator>/src/applications/transactions/editor/Phab ricatorApplicationTransactionEditor.php:861] [25-Nov-2015 19:10:21 Australia/Sydney] #10 <#2> PhabricatorApplicationTransactionEditor::applyTransactions(PhabricatorPaste, array) called at [<phabricator>/src/applications/transactions/editengine/PhabricatorEditEngine.php:702] [25-Nov-2015 19:10:21 Australia/Sydney] #11 <#2> PhabricatorEditEngine::buildEditResponse(PhabricatorPaste) called at [<phabricator>/src/applications/transactions/editengine/PhabricatorEditEngine.php:633] [25-Nov-2015 19:10:21 Australia/Sydney] #12 <#2> PhabricatorEditEngine::buildResponse() called at [<phabricator>/src/applications/paste/controller/PhabricatorPasteEditController.php:8] [25-Nov-2015 19:10:21 Australia/Sydney] #13 <#2> PhabricatorPasteEditController::handleRequest(AphrontRequest) called at [<phabricator>/src/aphront/configuration/AphrontApplicationConfiguration.php:237] [25-Nov-2015 19:10:21 Australia/Sydney] #14 phlog(AphrontQueryException) called at [<phabricator>/src/aphront/handler/PhabricatorDefaultRequestExceptionHandler.php:32] [25-Nov-2015 19:10:21 Australia/Sydney] #15 PhabricatorDefaultRequestExceptionHandler::handleRequestException(AphrontRequest, AphrontQueryException) called at [<phabricator>/src/aphront/configuration/AphrontApplicationConfiguration.php:6 32] [25-Nov-2015 19:10:21 Australia/Sydney] #16 AphrontApplicationConfiguration::handleException(AphrontQueryException) called at [<phabricator>/src/aphront/configuration/AphrontApplicationConfiguration.php:242] [25-Nov-2015 19:10:21 Australia/Sydney] #17 AphrontApplicationConfiguration::processRequest(AphrontRequest, PhutilDeferredLog, AphrontPHPHTTPSink, MultimeterControl) called at [<phabricator>/src/aphront/configuration/AphrontApplicationCo nfiguration.php:149] [25-Nov-2015 19:10:21 Australia/Sydney] #18 AphrontApplicationConfiguration::runHTTPRequest(AphrontPHPHTTPSink) called at [<phabricator>/webroot/index.php:17] [25-Nov-2015 19:10:21 Australia/Sydney] PHP Fatal error: Uncaught exception 'Exception' with message 'Process exited with an open transaction! The transaction will be implicitly rolled back. Calls to openTransaction() must always be paired with a call to saveTransaction() or killTransaction().' in /usr/src/libphutil/src/aphront/storage/connection/AphrontDatabaseTransactionState.php:78 Stack trace: #0 [internal function]: AphrontDatabaseTransactionState->__destruct() #1 {main} thrown in /usr/src/libphutil/src/aphront/storage/connection/AphrontDatabaseTransactionState.php on line 78