KB-1128 "ERROR .a.p.ANLYZE.i "Unexpected Exec Engine X was trying to send an Incremental Update."" error thrown when running an action in Appian


When a user clicks on an action in Appian, the user cannot see its configured task but gets a message saying "Action successfully completed". It is possible that there is an underlying issue in the Appian Engines if an error similar to the following is seen in db_PA*.log:

YYYY-MM-DD HH:MM:ss [PA000XX] {paXXX.kdb 15388} (Default) ERROR .a.p.ANLYZE.i "Unexpected Exec Engine 1 was trying to send an Incremental Update."


The above error means that the analytics engines could not recognize the execution engines. This occurs when .KDB files are copied over to an incorrect directory. It may be possible this issue originated during a migration that took place in the past.

The inconsistent engine will start but the errors in the logs will block it from taking on any new processes. This is the reason why the action skips to the success message directly without starting the process.


In order to get the problematic engine to receive new processes, please migrate the .KDB files into the correct directory from a backup. Make sure that all .KDB files from the source installation directory are copied to the corresponding engine directory in the target environment.

If restoring from a backup is not possible, please contact Appian Support for further assistance.

Affected Versions

This article applies to all versions of Appian.

Last Reviewed: February 2017