EL2NSYNC
Linux / POSIXERRORCriticalDeviceHIGH confidence
Level 2 Not Synchronized
Production Risk
Rare; indicates hardware/driver-level synchronization failure.
What this means
EL2NSYNC (errno 45) is a Linux/STREAMS-specific error indicating that level 2 of a layered protocol or device is not synchronized.
Why it happens
- 1STREAMS or layered device driver synchronization failure at protocol level 2
How to reproduce
STREAMS driver protocol level 2 sync failure.
trigger — this will error
trigger — this will error
// Returned by STREAMS drivers internally // errno = EL2NSYNC after failed sync operation
expected output
Level 2 not synchronized (EL2NSYNC)
Fix
Reset or reinitialize the device
WHEN When this error is returned from a STREAMS driver
Reset or reinitialize the device
// Close and reopen the device to reset state
close(fd);
fd = open("/dev/streams_device", O_RDWR);Why this works
Resetting the device connection forces protocol re-synchronization.
Sources
Official documentation ↗
Linux Programmer Manual errno(3)
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