Cisco APIC Installation and ACI Upgrade and Downgrade Guide

APIC upgrade detailed summary

Updated: July 12, 2026

Want to summarize with AI?

Provides a detailed summary of APIC upgrades.

The following section provides a detailed summary of APIC upgrades.

Understand APIC upgrade and downgrade stages

The APIC upgrade process progresses through several stages, each building on the completion of the previous one.

APIC upgrade process overview

Beginning with Cisco ACI release 6.2(1), the APIC upgrade process has been enhanced. The upgrade always starts on APIC1, which performs several cluster-wide upgrade stages and is the first APIC to be upgraded. When APIC1 is ready to upgrade itself, it hands off control to APIC2 using an internal API call. APIC1 then operates in node upgrade mode and completes its own upgrade. During this time, UI is redirected to APIC 2. APIC2 hands control back to APIC1 and UI is redirected. APIC1 continues upgrading the remaining APICs in the cluster in the same way. When all APICs have been upgraded to the target version, APIC1 performs the final cluster-wide stages and completes the upgrade cycle.

The upgrade process always starts on APIC1
APIC1 performs several cluster-wide upgrade stages and is the first APIC to be upgraded.
When APIC1 is ready to upgrade itself, it hands off control to APIC2 using an internal API call.
APIC1 then operates in node upgrade mode and completes its own upgrade.
During this time, UI is redirected to APIC 2 during this time.
APIC2 hands control back to APIC1 and UI is redirected.
APIC1 continues upgrading the remaining APICs in the cluster in the same way.
When all APICs have been upgraded to the target version, APIC1 performs the final cluster-wide stages and completes the upgrade cycle.

APIC upgrade stage table

The table below explains what occurs at each stage of the upgrade process.

Table 1. APIC Upgrade Stages
Name	Stage Level	Description
Catastrophic Failure Check	Cluster Wide	Initiate pre-upgrade validations to ensure upgrade can be performed.
Cluster Upgrade Preparation	Cluster Wide	Verify upgrade callbacks and set the cluster version to the requested upgrade version.
Upgrade Preparation	Node Level	Setup pre-upgrade state for all states.
Stage New OS	Node Level	Sets up the environment for data conversion using the extracted target image.
Freeze Database	Node Level	Freeze database for data conversion and monitor permdown completion.
Stop APIC Services	Node Level	Shut down services.
Stage Database Conversion	Node Level	Setup for data conversion.
Database Conversion	Node Level	Performs data conversion.
Install New OS	Node Level	Install the new OS.
Reboot	Node Level	Based on the upgrade, restart container or kexec the box to perform the reload operation.
Finalize OS Configuration	Node Level	Finalization of state done.
Cleanup	Node Level	Verify post upgrade activity.
Validate Cluster Health	Node Level	Verify that all nodes are in a healthy state.
Finalize Database State	Node Level	Verify if cluster is healthy
Validate Cluster Upgrade	Node Level	Perform post cluster upgrade checks.
Finalize Cluster State	Cluster Wide	Verify if post upgrade is completed on all shards and verify the APIC version
Validate Cluster State	Cluster Wide	Reset upgrade call backs on all APICs

Need help?

Open a support case

(Requires a Cisco Service Contract)

The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.