The release candidate of IOS XE 17.15.3 has been republished as a Beta release. This change is due to the discovery of a bug when upgrading from a CS firmware to an IOS XE firmware. During upgrades from CS firmware, networks may experience a brief (less than five minutes) risk of network instability while the CS configuration is removed and replaced with IOS XE configuration. Please note that this issue is not related to the quality or functionality of IOS XE 17.15.3 itself. A resolution for this issue is under development, and an updated Release Candidate will be provided upon validation.
You can find more details on the release notes, found under Organization > Monitor > Firmware Upgrades
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