[Nut-upsuser] NUT loses communications with the UPS

Roger Price roger at rogerprice.org
Sun May 24 20:16:31 BST 2020

On Sun, 24 May 2020, P├ęter Szabados wrote:

> I have an APC Back-UPS ES 550G. I use the usbhid-ups driver, which works fine 
> most of the time. However, after a few hours of running, it starts to 
> broadcast messages on the network that the UPS is not available, and any 
> attempted queries will return "Data stale". Restarting the driver solves the 
> problem, at least for the next few hours.

This is a regular question in this list, and it looks as if fixing the problem 
will require some detective work, and detailed tracing.

What does command lsusb report for the your APC Back-UPS ES 550G?  Is this 
idVendor and idProduct in /usr/lib/udev/rules.d/62-nut-usbups.rules ?

In general, should users expect a usb UPS unit to work correctly if the unit is 
not in the 62-nut-usbups.rules file?  Does permanent "Data stale" occur even for 
units that are in that file?

Have you tried increasing MAXAGE in upsd.conf as described in the FAQ 


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