Symfony version(s) affected

6.3

Description

TL;DR

When upgrading to>=6.3, all tagged cache item will be lost (triggering a massive cache miss)

Details

The way cache tag are storedhave changed in Symfony 6.3. I'm not sure of the exact mecanism but I'm pretty sure all tagged cache item have been regenerated without much issue (except a load spike ?).

The issue is worse in multi-server applications. In our (very intensive) setup, we tried the upgrade with a rolling update : 1 pod with sf6.3 and a few tens with sf6.2, for about 1h, and we noticed the cache was invalidated all the time, provoking a lot of errors (mostly due to rate-limiting from a third-party).

How to reproduce

1. Create some long lived cache item in Symfony 6.2 (we use Redis if it's important)
2. Upgrade to Symfony 6.3 without changing the configuration
3. Triggering the cache should result in a miss

Possible Solution

I'll let you decide if you want totemporarily support both tag formats.

A note in the changelog would be nice to help concerned people be aware of this situation, or at least diagnose it more easily.

Our workaround involved changing the cache seed to avoid weird interaction between both versions.

Additional Context

No response