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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.
<APPIAN_HOME>/logs
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 and provide a 15 minute window for an application server restart, during which the site will be unavailable. High Availability sites require a 30 minute window for a rolling application server restart with no downtime.
This article applies to all versions of Appian.
Last Reviewed: June 2021