Poll UPS [nutdev1] failed - Data stale

[axet]

Every time after machine reboot I got "Data stale" error after about 1 minute. But when I manual restart the driver UPS works without issues.

I start machine at 4:17, driver failed at 04:18:56. After 'systemctl restart nut-driver@nutdev1' everything works just fine.

Tested for nut 2.8.1 and also 2.8.4, debian trixie.
"Ippon Back Basic 650" ttyUSB0 model

мар 21 04:17:52 axet-desktop kernel: Linux version 6.19.6+deb13-amd64 (debian-kernel@lists.debian.org) (x86_64-linux-gnu-gcc-14 (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44) #1 SMP PREEMPT_DYNAMIC Debian 6.19.6-2~bpo13+1 (2026-03-14)
мар 21 04:17:52 axet-desktop systemd[1]: Created slice system-nut\x2ddriver.slice - Slice /system/nut-driver.
мар 21 04:17:53 axet-desktop systemd-tmpfiles[800]: /usr/lib/tmpfiles.d/nut-common-tmpfiles.conf:8: Duplicate line for path "/run/nut", ignoring.
мар 21 04:17:57 axet-desktop systemd[1]: Started nut-driver-enumerator.path.
мар 21 04:17:57 axet-desktop systemd[1]: Starting nut-driver-enumerator.service - Network UPS Tools - enumeration of configure-file devices into systemd unit instances...
мар 21 04:17:57 axet-desktop systemd[1]: Starting nut-driver@nutdev1.service - Network UPS Tools - device driver for nutdev1...
мар 21 04:17:57 axet-desktop avahi-daemon[913]: Loading service file /services/nut.service.
мар 21 04:17:57 axet-desktop nut-driver-enumerator[950]: Sat Mar 21 01:17:57 UTC 2026 : OK: No changes to reconcile between systemd service instances and device configurations in '/etc/nut/ups.conf'
мар 21 04:17:57 axet-desktop systemd[1]: nut-driver-enumerator.service: Deactivated successfully.
мар 21 04:17:57 axet-desktop systemd[1]: Finished nut-driver-enumerator.service - Network UPS Tools - enumeration of configure-file devices into systemd unit instances.
мар 21 04:17:59 axet-desktop avahi-daemon[913]: Service "axet-desktop" (/services/nut.service) successfully established.
мар 21 04:17:59 axet-desktop nut-driver@nutdev1[1093]: Protocol [235.] is not supported by this driver
мар 21 04:18:00 axet-desktop nut-driver@nutdev1[1093]: Protocol [235.] is not supported by this driver
мар 21 04:18:00 axet-desktop nut-driver@nutdev1[1093]: Protocol [235.] is not supported by this driver
мар 21 04:18:01 axet-desktop nut-driver@nutdev1[1093]: Using protocol: Megatec 0.07
мар 21 04:18:01 axet-desktop nut-driver@nutdev1[1093]: No values for battery high/low voltages
мар 21 04:18:01 axet-desktop nut-driver@nutdev1[1093]: Using 'guesstimation' (low: 10.400000, high: 13.000000)!
мар 21 04:18:01 axet-desktop nut-driver@nutdev1[1093]: Autodetected 1 as number of battery packs [12/13.70]
мар 21 04:18:01 axet-desktop nut-driver@nutdev1[1093]: Battery runtime will not be calculated (runtimecal not set)
мар 21 04:18:01 axet-desktop nutdrv_qx[1093]: No values for battery high/low voltages
мар 21 04:18:01 axet-desktop nutdrv_qx[1093]: Using 'guesstimation' (low: 10.400000, high: 13.000000)!
мар 21 04:18:01 axet-desktop nutdrv_qx[1093]: Autodetected 1 as number of battery packs [12/13.70]
мар 21 04:18:01 axet-desktop nutdrv_qx[1093]: Battery runtime will not be calculated (runtimecal not set)
мар 21 04:18:01 axet-desktop nutdrv_qx[3904]: Startup successful
мар 21 04:18:01 axet-desktop nutdrv_qx[3904]: upsnotify: notify about state 2 with libsystemd: was requested, but not running as a service unit now, will not spam more about it
мар 21 04:18:01 axet-desktop nut-driver@nutdev1[955]: Network UPS Tools - UPS driver controller 2.8.1
мар 21 04:18:01 axet-desktop nutdrv_qx[3904]: upsnotify: failed to notify about state 2: no notification tech defined, will not spam more about it
мар 21 04:18:01 axet-desktop nutdrv_qx[3904]: upsnotify: logged the systemd watchdog situation once, will not spam more about it
мар 21 04:18:01 axet-desktop systemd[1]: Started nut-driver@nutdev1.service - Network UPS Tools - device driver for nutdev1.
мар 21 04:18:01 axet-desktop systemd[1]: Reached target nut-driver.target - Network UPS Tools - target for power device drivers on this system.
мар 21 04:18:01 axet-desktop systemd[1]: Starting nut-server.service - Network UPS Tools - power devices information server...
мар 21 04:18:01 axet-desktop systemd[1]: Started nut-server.service - Network UPS Tools - power devices information server.
мар 21 04:18:01 axet-desktop systemd[1]: Starting nut-monitor.service - Network UPS Tools - power device monitor and shutdown controller...
мар 21 04:18:01 axet-desktop nut-server[3912]: fopen /run/nut/upsd.pid: No such file or directory
мар 21 04:18:01 axet-desktop nut-server[3912]: Could not find PID file '/run/nut/upsd.pid' to see if previous upsd instance is already running!
мар 21 04:18:01 axet-desktop nut-server[3912]: listening on ::1 port 3493
мар 21 04:18:01 axet-desktop nut-server[3912]: listening on 127.0.0.1 port 3493
мар 21 04:18:01 axet-desktop nut-server[3912]: Connected to UPS [nutdev1]: nutdrv_qx-nutdev1
мар 21 04:18:01 axet-desktop nut-server[3912]: Found 1 UPS defined in ups.conf
мар 21 04:18:01 axet-desktop upsd[3912]: Connected to UPS [nutdev1]: nutdrv_qx-nutdev1
мар 21 04:18:01 axet-desktop systemd[1]: Started nut-monitor.service - Network UPS Tools - power device monitor and shutdown controller.
мар 21 04:18:01 axet-desktop upsd[3912]: /etc/nut/upsd.users is world readable
мар 21 04:18:01 axet-desktop nut-server[3912]: /etc/nut/upsd.users is world readable
мар 21 04:18:01 axet-desktop nut-server[3912]: Running as foreground process, not saving a PID file
мар 21 04:18:01 axet-desktop nut-server[3912]: upsnotify: notify about state 2 with libsystemd: was requested, but not running as a service unit now, will not spam more about it
мар 21 04:18:01 axet-desktop nut-server[3912]: upsnotify: failed to notify about state 2: no notification tech defined, will not spam more about it
мар 21 04:18:01 axet-desktop nut-server[3912]: upsnotify: logged the systemd watchdog situation once, will not spam more about it
мар 21 04:18:01 axet-desktop systemd[1]: Reached target nut.target - Network UPS Tools - target for power device drivers, data server and monitoring client (if enabled) on this system.
мар 21 04:18:01 axet-desktop nut-monitor[3914]: fopen /run/nut/upsmon.pid: No such file or directory
мар 21 04:18:01 axet-desktop nut-monitor[3914]: Could not find PID file to see if previous upsmon instance is already running!
мар 21 04:18:01 axet-desktop nut-monitor[3914]: UPS: nutdev1 (primary) (power value 1)
мар 21 04:18:01 axet-desktop nut-monitor[3914]: Using power down flag file /etc/killpower
мар 21 04:18:01 axet-desktop nut-monitor[3914]: /etc/nut/upsmon.conf line 10: invalid directive OVERDURATION -1
мар 21 04:18:01 axet-desktop nut-monitor[3914]: /etc/nut/upsmon.conf line 14: invalid directive ALARMCRITICAL 1
мар 21 04:18:01 axet-desktop nut-monitor[3919]: Init SSL without certificate database
мар 21 04:18:01 axet-desktop nut-monitor[3919]: upsnotify: notify about state 2 with libsystemd: was requested, but not running as a service unit now, will not spam more about it
мар 21 04:18:01 axet-desktop nut-monitor[3919]: upsnotify: failed to notify about state 2: no notification tech defined, will not spam more about it
мар 21 04:18:01 axet-desktop nut-monitor[3919]: upsnotify: logged the systemd watchdog situation once, will not spam more about it
мар 21 04:18:01 axet-desktop nut-monitor[3919]: Login on UPS [nutdev1] failed - got [ERR ACCESS-DENIED]
мар 21 04:18:02 axet-desktop nutdrv_qx[3904]: sock_connect: enabling asynchronous mode (auto)
мар 21 04:18:51 axet-desktop nut-server[3912]: Data for UPS [nutdev1] is stale - check driver
мар 21 04:18:51 axet-desktop upsd[3912]: Data for UPS [nutdev1] is stale - check driver
мар 21 04:18:51 axet-desktop nut-monitor[3919]: Poll UPS [nutdev1] failed - Data stale
мар 21 04:18:51 axet-desktop nut-monitor[3919]: Communications with UPS nutdev1 lost
мар 21 04:18:51 axet-desktop nut-monitor[8822]: Network UPS Tools upsmon 2.8.1
мар 21 04:18:56 axet-desktop nut-monitor[3919]: Poll UPS [nutdev1] failed - Data stale
мар 21 04:19:00 axet-desktop systemd[1]: Stopping nut-driver@nutdev1.service - Network UPS Tools - device driver for nutdev1...
мар 21 04:19:00 axet-desktop nutdrv_qx[3904]: Signal 15: exiting
мар 21 04:19:00 axet-desktop upsd[3912]: Can't connect to UPS [nutdev1] (nutdrv_qx-nutdev1): No such file or directory
мар 21 04:19:00 axet-desktop nut-server[3912]: Can't connect to UPS [nutdev1] (nutdrv_qx-nutdev1): No such file or directory
мар 21 04:19:01 axet-desktop nut-driver@nutdev1[9425]: fopen /run/nut/nutdrv_qx-nutdev1.pid: No such file or directory
мар 21 04:19:01 axet-desktop nut-driver@nutdev1[9425]: Network UPS Tools - UPS driver controller 2.8.1
мар 21 04:19:01 axet-desktop systemd[1]: nut-driver@nutdev1.service: Deactivated successfully.
мар 21 04:19:01 axet-desktop systemd[1]: Stopped nut-driver@nutdev1.service - Network UPS Tools - device driver for nutdev1.
мар 21 04:19:01 axet-desktop systemd[1]: Starting nut-driver@nutdev1.service - Network UPS Tools - device driver for nutdev1...
мар 21 04:19:01 axet-desktop nut-monitor[3919]: Poll UPS [nutdev1] failed - Driver not connected
мар 21 04:19:04 axet-desktop nut-driver@nutdev1[9478]: Protocol [235.] is not supported by this driver
мар 21 04:19:04 axet-desktop nut-driver@nutdev1[9478]: Protocol [235.] is not supported by this driver
мар 21 04:19:04 axet-desktop nut-driver@nutdev1[9478]: Protocol [235.] is not supported by this driver
мар 21 04:19:05 axet-desktop nut-driver@nutdev1[9478]: Using protocol: Megatec 0.07
мар 21 04:19:05 axet-desktop nut-driver@nutdev1[9478]: No values for battery high/low voltages
мар 21 04:19:05 axet-desktop nut-driver@nutdev1[9478]: Using 'guesstimation' (low: 10.400000, high: 13.000000)!
мар 21 04:19:05 axet-desktop nut-driver@nutdev1[9478]: Autodetected 1 as number of battery packs [12/13.70]
мар 21 04:19:05 axet-desktop nut-driver@nutdev1[9478]: Battery runtime will not be calculated (runtimecal not set)
мар 21 04:19:05 axet-desktop nutdrv_qx[9478]: No values for battery high/low voltages
мар 21 04:19:05 axet-desktop nutdrv_qx[9478]: Using 'guesstimation' (low: 10.400000, high: 13.000000)!
мар 21 04:19:05 axet-desktop nutdrv_qx[9478]: Autodetected 1 as number of battery packs [12/13.70]
мар 21 04:19:05 axet-desktop nutdrv_qx[9478]: Battery runtime will not be calculated (runtimecal not set)
мар 21 04:19:06 axet-desktop nutdrv_qx[9539]: Startup successful
мар 21 04:19:06 axet-desktop nutdrv_qx[9539]: upsnotify: notify about state 2 with libsystemd: was requested, but not running as a service unit now, will not spam more about it
мар 21 04:19:06 axet-desktop nut-driver@nutdev1[9451]: Network UPS Tools - UPS driver controller 2.8.1
мар 21 04:19:06 axet-desktop nutdrv_qx[9539]: upsnotify: failed to notify about state 2: no notification tech defined, will not spam more about it
мар 21 04:19:06 axet-desktop nutdrv_qx[9539]: upsnotify: logged the systemd watchdog situation once, will not spam more about it
мар 21 04:19:06 axet-desktop systemd[1]: Started nut-driver@nutdev1.service - Network UPS Tools - device driver for nutdev1.
мар 21 04:19:06 axet-desktop nut-monitor[3919]: Poll UPS [nutdev1] failed - Driver not connected
мар 21 04:19:06 axet-desktop nut-server[3912]: Connected to UPS [nutdev1]: nutdrv_qx-nutdev1
мар 21 04:19:06 axet-desktop upsd[3912]: Connected to UPS [nutdev1]: nutdrv_qx-nutdev1
мар 21 04:19:06 axet-desktop nutdrv_qx[9539]: sock_connect: enabling asynchronous mode (auto)
мар 21 04:19:11 axet-desktop nut-monitor[3919]: Communications with UPS nutdev1 established
мар 21 04:19:11 axet-desktop nut-monitor[9944]: Network UPS Tools upsmon 2.8.1

status

Init SSL without certificate database
battery.charge: 100
battery.voltage: 13.7
battery.voltage.high: 13.00
battery.voltage.low: 10.40
battery.voltage.nominal: 12.0
device.mfr: 000000000000000
device.model: Back Basi
device.type: ups
driver.debug: 0
driver.flag.allow_killpower: 0
driver.name: nutdrv_qx
driver.parameter.pollfreq: 30
driver.parameter.pollinterval: 2
driver.parameter.port: /dev/ttyUSB0
driver.parameter.synchronous: auto
driver.state: quiet
driver.version: 2.8.1
driver.version.data: Megatec 0.07
driver.version.internal: 0.36
driver.version.usb: libusb-1.0.28 (API: 0x100010a)
input.current.nominal: 2.0
input.frequency: 49.7
input.frequency.nominal: 50
input.voltage: 235.0
input.voltage.fault: 235.0
input.voltage.nominal: 220
output.voltage: 237.0
ups.beeper.status: enabled
ups.delay.shutdown: 30
ups.delay.start: 180
ups.firmware: 650 PE024
ups.load: 19
ups.status: OL
ups.temperature: 25.0
ups.type: offline / line interactive

ups.conf

maxretry = 3

[nutdev1]
        driver = "nutdrv_qx"
        port = "/dev/ttyUSB0"

[axet]

exec upscmd -u $LOGIN -p $PASS $DEV beeper.disable crashing port. is here a autorestart?

[jimklimov]

This is indeed strange. After the driver restart, does it work "forever" or also for a few minutes like with initial start?

I wonder if something else in the system might intervene (e.g. cause USB rescan, steal devices to read them for something else assuming this is that other program's serial port)? Is there something else starting another copy of the driver itself? Maybe some getty trying to spawn a Linux console on this serial port?

See https://github.com/networkupstools/nut/wiki/Changing-NUT-daemon-debug-verbosity about bumping verbosity of the driver, so you can log in more detail what happens to the driver before it is deemed stale (e.g. device node lost due to whatever, and reconnection did not kick in).

Also (as root) check journalctl -xn to see log entries from all services intermixed, so you might find if anyone else suspicious started during that minute that the driver worked and then didn't.

[jimklimov]

...crashing port. is here a autorestart?

What did you mean by this? autorestart of whom? crashing how - serial port with the UPS no longer responding?

exec upscmd -u $LOGIN -p $PASS $DEV beeper.disable

Notably exec may be wrong here, it substitutes the shell for another process using the same PID, so when upscmd ends whichever way, your shell session is gone. Is that the crash you see?

[axet]

It seems like driver sent to "stale" after using upscmd using only two commands:

• upscmd -u $LOGIN -p $PASS $DEV beeper.disable
• upscmd -u $LOGIN -p $PASS $DEV beeper.toggle

I sent support IPPON message about why "frimware" failed with those two commands. But question is why 'nut' does not restart driver when it's "stale".

PS: exec was part of my "ups" shell script.

[jimklimov]

Restarting depends on a number of things. One is actually finding that the driver is stuck. For example, if for some reason a read/write operation never returns from a kernel syscall, and the driver was not coded for time-limited operations but used read/write same as it did 20 years ago, and nobody changed that since, then the driver won't know it should restart itself. Or attempt a reconnection.

Another thing, again with all drivers coming from different authors and decades, is whether they would try to restart at all, even if an I/O error is diagnosed, or if they would keep trying to use the no-longer-valid file descriptor, for example. Generally newer NUT versions should fare better with this, but it may not have been addressed in all NUT programs yet.

Sometimes device data becomes stale because the UPS I/O controller hangs/restarts/... or just is overwhelmed and lags. Those chips or NMC cards are also computers, often small and cheap ones, with all that comes out from that. In these cases, often keeping up the retry loop with same file descriptor is the right thing to do, as eventually the chip on the other side comes to its senses. But sometimes the act of stopping and starting the driver causes some activity on the (more commonly USB) bus which restarts or unblocks that chip, or system buffers associated with that.

Looking at current code however, with nutdrv_qx there is reconnection code for USB links, where I/O errors are reported by the library. Currently there is none for serial-port links (like /dev/ttyUSB0 in your case).

I suspect (your logs might confirm) that something in your system start-up causes a USB bus reset or re-enumeration, so the devfs node for /dev/ttyUSB0 disappears and re-appears as far as the kernel is concerned, rendering open connections invalid. I suppose hot-plugging of serial port hardware was not a design consideration when all those drivers started out. Hopefully the logs would expose the error code to hunt for :)