%PM-4-ERR_DISABLE: link-flap error detected on Gi1/0/24, putting Gi1/0/24 in err-disable state
In plain English: The switch saw the link on this port drop and come back 5 times within 10 seconds (the default flap setting) and shut the port down on purpose to protect the network.
Platform: Cisco IOS / IOS XE. Values shown are the documented defaults — confirm them on your platform with the check commands below.
What it means
The switch saw the link on this port drop and come back 5 times within 10 seconds (the default flap setting) and shut the port down on purpose to protect the network. The port stays down until someone fixes the cause and re-enables it. This is the switch doing its job, not the switch failing.
Likely causes, in order
A failing patch cable or a bad cable termination — the most common cause by far.
A dying SFP/optic, or dirty fiber ends.
The device at the other end: a failing NIC, a docking station, or power-saving settings dropping the link.
A person physically unplugging and re-plugging the cable over and over.
Check, in order
show interfaces status err-disabledLists every port the switch has shut off, so you can see whether this is one port or many.
show logging | include ERR_DISABLEShows the exact reason the switch recorded and when each shutdown happened. The times often tell the story.
show interfaces Gi1/0/24 counters errorsClimbing CRC and input errors point at the physical layer: cable, optic, or port. Clean counters point at the device at the other end.
The fix
Replace the patch cable first — it is the cheapest part and the usual culprit. Then the optic if errors continue.
Move the cable to a spare port. If the problem follows the cable, the switch port was never the problem.
Bring the port back with shut, then no shut, and watch it. Do not turn on automatic errdisable recovery until the cause is found — the port will just flap forever and the alarm goes quiet while the fault stays.
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Full case: this error is one stop in a bigger fault. Work the complete playbook: Port Keeps Going Err-Disabled — checks, ranked causes, the fix, and verification.