Failure message in DOF's log
What it means
The latest session recorded in DOF's log contains a failure message about a controller or the configuration.
Why it happens
"DirectOutput.log", beside "DirectOutput.dll", records what DOF does in each session. The scan reads the latest session and keeps the last line that matches a known DOF failure message: a failed USB write to a LedWiz board, an unreadable configuration file or a missing COM port, for example. That line shows that a failure was recorded during that session; it does not give the cause, nor the current state of the controller or of the configuration. A DOF setting can place the log elsewhere, in which case the scan does not see it.
How to fix it
Check that the controller named in the failure line of "DirectOutput.log" is plugged in and powered, then start a table. If that line says a configuration file could not be read, create that file again with the DOF Config Tool. A new scan after playing a table shows whether the error comes back.
How Pincab Toolbox detects it
"DirectOutput.dll" is found by the scan, "DirectOutput.log" is beside it, and after the last session marker ("DirectOutput logger initialized") a line matches a known failure message. The scan changed nothing.
Check your own pincab
Pincab Toolbox is a free Windows scanner for Visual Pinball X and PinUP Popper. It finds and explains problems like this one. No account, no telemetry.
Download for freeCovered: Visual Pinball X (10.x) and PinUP Popper. Partly covered, read only: PinballX and PinballY (their settings and game lists). Not covered: Future Pinball, Pinball FX, Visual Pinball 9 and the other frontends.