我们以ojs系统为例：
PHP Fatal error: Uncaught Error: Call to a member function getId() on null in /esci/data/html/classes/install/Upgrade.inc.php:1019
Stacktrace:
#0 /esci/data/html/lib/pkp/classes/install/Installer.inc.php(415): Upgrade->convertSupplementaryFiles(Object(Upgrade), Array)
#1 /esci/data/html/lib/pkp/classes/install/Installer.inc.php(265): Installer->executeAction(Array)
#2 /esci/data/html/lib/pkp/classes/install/Installer.inc.php(186): Installer->executeInstaller()
#3 /esci/data/html/lib/pkp/classes/cliTool/UpgradeTool.inc.php(88): Installer->execute()
#4 /esci/data/html/lib/pkp/classes/cliTool/UpgradeTool.inc.php(64): UpgradeTool->upgrade()
#5 /esci/data/html/tools/upgrade.php(34): UpgradeTool->execute()
#6 {main}
thrown in /esci/data/html/classes/install/Upgrade.inc.php on line 1019
Fatal error: Uncaught Error: Call to a member function getId() on null in /esci/data/html/classes/install/Upgrade.inc.php:1019
Stacktrace:
#0 /esci/data/html/lib/pkp/classes/install/Installer.inc.php(415): Upgrade->convertSupplementaryFiles(Object(Upgrade), Array)
#1 /esci/data/html/lib/pkp/classes/install/Installer.inc.php(265): Installer->executeAction(Array)
#2 /esci/data/html/lib/pkp/classes/install/Installer.inc.php(186): Installer->executeInstaller()
#3 /esci/data/html/lib/pkp/classes/cliTool/UpgradeTool.inc.php(88): Installer->execute()
#4 /esci/data/html/lib/pkp/classes/cliTool/UpgradeTool.inc.php(64): UpgradeTool->upgrade()
#5 /esci/data/html/tools/upgrade.php(34): UpgradeTool->execute()
#6 {main}
thrown in /esci/data/html/classes/install/Upgrade.inc.php on line 1019
技术全文：www.ojs.net.cn/455.html
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