After an upgrade or site restart, process models fail to save with the following error:
Non-nullable input ACP(s) for unattended node(s) must not be null: isAsynchronous
Users may also see *.l files generated in the <APPIAN_HOME>/logs directory after the upgrade or site restart. More information about these log files can be found here.
The application server is in an inconsistent state due to an engine issue, usually an engine roll back or disconnect.
Follow KB-1232 to restart the application server and clear application server cache.
Open a support case with Appian Support to coordinate an application server restart for the environment.
This article applies to all versions of Appian.
Last Reviewed: June 2021
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