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The %SYS-3-SYS_MEMERR: syslog error message is displayed on a Cisco Catalyst 6500 or 6000 series switch running CatOS

Core issue

The %SYS-3-SYS_MEMERR: [chars] while [chars] address 0x[hex] message indicates that the memory management has detected memory corruption. The first [chars] could indicate one of these issues:

  • Out of range

  • Bad alignment

  • Block is not free

  • No clusters left

  • Back pointer mismatch
  • Bad magic number
  • Succeeding block out of range
  • Succeeding block improperly aligned
  • Preceding block out of range
  • Preceding block improperly aligned

  • Bad process id

The second [chars] could be freeing, getting, or allocating. The [hex] field is the block address to be freed, obtained, or allocated.

For example, the %SYS-3-SYS_MEMERR: No clusters left while allocating for address 0x409c1900 message and the SYS-3-SYS_MEMERR: Null cluster while getting next from address 0x30e8eda0 message can sometimes occur together. These messages indicate that the system could be overloaded. The system can recover properly if the heavy load is temporary.

The %SYS-3-SYS_MEMERR error message indicates that during the memory block, the memory management found that information was corrupted. This problem occurs occasionally, with no ill effects on the switch.


As a first resolution step, check to see whether the system is overloaded. If the system is overloaded, reduce the load to resolve this issue.

If it is a first occurrence, monitor the switch for at least 48 hours. If it does not re-occur, then it can be considered as a Single Event Upset (SEU).

If this error occurs several times over a short period of time, check to see if the block address that the error messages mention is the same. If the block address is the same, there is a possibility that a particular sector on the memory chip is bad and must be replaced.

Error message