Cat4500e-universalk9.spa.03.11.04.e.152-7.e4.bin -

CPU spikes to 99% after upgrade. Cause: The old spanning-tree vlan 1-4094 macro. This image introduces per-VLAN rapid-pvst threads. Fix: no spanning-tree vlan 1-4094 then specifically enable only used VLANs.

Let’s dissect cat4500e-universalk9.spa.03.11.04.e.152-7.e4.bin : cat4500e-universalk9.spa.03.11.04.e.152-7.e4.bin

SSH fails with no matching key exchange method . Cause: Your old SSH client lacks modern KEX. This image disables diffie-hellman-group1-sha1 . Fix: On client side, or on switch: ip ssh server algorithm kex diffie-hellman-group14-sha1 CPU spikes to 99% after upgrade

conf t no boot system boot system flash:cat4500e-universalk9.spa.03.11.04.e.152-7.e4.bin config-register 0x2102 end write memory If your 4500E is in VSS (Virtual Switching System), you must upgrade the Standby switch first, then failover, then upgrade the former Active. Command: redundancy force-switchover after standby is fully loaded. Phase 4: Activation & Rollback Plan reload in 30 (Reloads in 30 minutes – use 'reload cancel' if issues) reload Rollback: If the switch fails to boot three times, ROMMON loads automatically. In ROMMON: Fix: no spanning-tree vlan 1-4094 then specifically enable