Middleware connections, startup and dependency errors
Check connected-client counts in middleware logs and capture startup or dependency failures.
Start with the error
Start with nxtwash logs. Capture the exact startup failure, the machine role, the software release, and the time. Avoid including configuration secrets in an exported log excerpt.
Connected devices in the middleware logs
Middleware logs help identify fewer or more client connections than expected. Read the logs on the middleware computer for the correct lane and instance:
nxtwash logs
For additional instance 1, use nxtwash logs 1; choose the instance assigned to the device being checked. Ctrl+C stops following the logs without stopping middleware.
A zero-client example:
[INFO] [src.event.manager] Sent event to 0 clients, KeepAliveEvent()
This example shows no connected clients on that middleware instance at those times. Compare the reported count with the devices/client sessions expected to be connected to that instance:
| Observation | What to check |
|---|---|
| Zero clients when a device should be connected | Verify the expected app is open in an approved Chromium-based browser, its network and middleware address, and that these are the correct instance's logs. |
| Fewer clients than expected | Identify which expected device or client session is missing; compare its connection indicator and settings. |
| More clients than expected | Identify the extra client connections and confirm which devices or sessions should be attached. |
Record the instance, timestamp, expected connections and observed count for support. Use the site's expected client list; there is no universal correct number. The log reports client connections, so do not treat the count as an inventory of every physical USB, serial or network peripheral. Validate recognition, payments and wash sending separately where applicable.
Marshmallow import failure
The documented incident was:
ImportError: cannot import name 'pprint' from 'marshmallow'
The failing example had Marshmallow 4.0.0; the working comparison had 3.20.1.
Inspect the installed package:
pip show marshmallow
Interpretation
Those version numbers describe the recorded incident. Compare against a working machine on the same supported NXT Wash release and environment before selecting a fix. Do not downgrade a current installation solely because an older incident used 3.20.1.
Recovery check
After the technician's approved repair and service restart, confirm the startup error is gone and test the connected lane functions. Record the release, environment, error, and resolution.
POS connection indicator
Check the POS-to-middleware status: the red Disconnected display below Scanning LP means the app is disconnected. Any other state in the open POS app means it is connected to middleware.
Middleware installer and commands
Install and commission middleware, or open the command reference for logs, service checks, updates, certificates and cash maintenance.