PHP message: [2018-04-30 17:22:56] EXCEPTION: (PHPExcel_Exception) Invalid cell coordinate [1 at [/opt/PHPExcel/Classes/PHPExcel/Cell.php:594] PHP message: arcanist(head=master, ref.master=ad3087e5e151), phabricator(head=master, ref.master=15e6e2adea61), phutil(head=master, ref.master=20eff1c8d14f) PHP message: #0 <#2> PHPExcel_Cell::coordinateFromString(string) called at [/opt/PHPExcel/Classes/PHPExcel/Worksheet.php:1218] PHP message: #1 <#2> PHPExcel_Worksheet::createNewCell(string) called at [/opt/PHPExcel/Classes/PHPExcel/Worksheet.php:1178] PHP message: #2 <#2> PHPExcel_Worksheet::getCell(string) called at [/opt/PHPExcel/Classes/PHPExcel/Worksheet.php:1085] PHP message: #3 <#2> PHPExcel_Worksheet::setCellValue(string, string, boolean) called at [/src/infrastructure/export/format/PhabricatorExcelExportFormat.php:73] PHP message: #4 <#2> PhabricatorExcelExportFormat::addHeaders(array) called at [/src/infrastructure/export/engine/PhabricatorExportEngine.php:126] PHP message: #5 <#2> PhabricatorExportEngine::exportFile() called at [/src/applications/search/controller/PhabricatorApplicationSearchController.php:514] PHP message: #6 <#2> PhabricatorApplicationSearchController::processExportRequest() called at [/src/applications/search/controller/PhabricatorApplicationSearchController.php:80] PHP message: #7 <#2> PhabricatorApplicationSearchController::processRequest() called at [/src/aphront/AphrontController.php:29] PHP message: #8 <#2> AphrontController::handleRequest(AphrontRequest) called at [/src/aphront/AphrontController.php:71] PHP message: #9 <#2> AphrontController::delegateToController(PhabricatorApplicationSearchController) called at [/src/applications/maniphest/controller/ManiphestTaskListController.php:20] PHP message: #10 <#2> ManiphestTaskListController::handleRequest(AphrontRequest) called at [/src/aphront/