[Escalated to WPML Developers team] Object Cache Pro causing WPML issues

Hi Subash,

Thank you. I'll wait for your findings.

I'm not sure if this is an edge cache. Many sites are hosted on Cloudways and the "challenges" with Object Cache Pro and WPML are well-known and reported by others too here in the support forum.

Now, there's one more thing I wanted to try. Based on info on https://wpml.org/errata/problems-with-buddypress-multilingual-and-redis-object-cache/ and hidden link, I am thinking I don't need to set 'WP_REDIS_IGNORED_GROUPS', but I need to add 'non_persistent_groups' to 'WP_REDIS_CONFIG'.

'WP_REDIS_CONFIG' was already present in my wp-config.php, so I extended it manually. It now looks like this:

define('WP_REDIS_CONFIG', [
'token' => "...",
'host' => '127.0.0.1',
'port' => ...,
'database' => "...",
'timeout' => 2.5,
'read_timeout' => 2.5,
'split_alloptions' => true,
'async_flush' => true,
'client' => 'phpredis',
'compression' => 'zstd',
'serializer' => 'igbinary',
'prefetch' => true,
'debug' => false,
'save_commands' => false,
'prefix' => DB_NAME,
'non_persistent_groups' => ['advanced-ads', 'WPML_TM_ICL_Translations', 'sitepress-multilingual-cms', ],
]);

Does this make sense?

Arno

Hi Subash,

After a few days, I can conclude that issues 1 and 3 are not solved with this new configuration. Issue 2 was not tested yet.

For now, we disable Object Cache Pro to work with WPML in an efficient manner. We then enable it again when the translation manager is done. That's kind of a hassle because the manager has no admin access, so I need to do that.

I hope your developers can look into this. This might not even be a bug that requires a code fix. We probably only need to know which database queries are affected, and which exclusions/persistent groups need to be configured to bypass the cache.

Thanks,
Arno

Hi Subash,

I just spent quite a while to try and reproduce this on purpose. I even tried different user roles. Everything worked fine. That's the issue here: it works fine for some time, then all of a sudden the issues I mentioned occur again and the translation manager asks me to disable Object Cache Pro to solve it. I can't predict when and why the issues occur.

That's why I think it's more important to sort out which WPML database queries never need to be cached, and focus on that rather than trying to reproduce this. I can't understand how the theme or other plugins would cause this. Not saying that it's impossible but it seems unlikely for this issue.

I will keep testing though, and if I have more details I will let you know for sure.

Thanks,
Arno

Hi Subash,

I may have found something that helps you to figure this out. Here's another issue with Object Cache Pro:

1. Add a new user to WordPress (Subscriber role).
2. Add the new user as a translator to WPML.
3. Go to WPML Translation Management > Translation Basket and try to select the new translator under "Choose translator or Translation Service". The new translator is not listed. After 20-30 minutes it was still not listed. Then I flushed the cache of Object Cache Pro and that solved it immediately.

I think this is another example of a WPML database query that should bypass the cache, or if adding a translator it should flush that part of the cache if possible. I'm not sure what's best.

Either way, this might be easier to reproduce and hopefully leads to a solution.

Kind regards,
Arno

Hi Subash,

When do you expect an update from the 2nd tier and an ETA for a fix?

Have a good weekend,
Arno