You can not change the default language ,Becuase you are using variable products

@emilybkk the plugin make the following point very clear in its description

The plugin support variable products , but using them will disallow you to change the default language , because of the way the plugin implements this support. So you have to make sure to choose the default language before you start adding new variable products.

the solution for this in current plugin version is :

1. Deactivate the plugin
2. Reset polylang default language to same language you used when you added your variable products
3. Reactivate the plugin

I see. So maybe the 404 may problem with the Polylang itselves ??

It can’t find the product which is another language. It only display product under default language.

Do you have any idea to fix this? Please help.

Try with another site. It still work well. Thank you.

Finally, after try many solution. I think the problem is the 5.3.28 php version on my hosting. When I use polylang+Hyyan+woocommerce on another hosting which has php 5.4.37 I get no problem at all.

Hope this help.
Thank you very much

@emilybkk sorry for late answer , and thank very much for your valuable feedback , I’ll try to check what is wrong with when php5.3.28 is used.

Hi. I have some update again. Sound I am annoying you guys haha.

Well after I ask my hosting to upgrade the Php version for me and guess what? It still not working.

Last try before moving to WPML I deleted everything and do reinstall WordPress manually (It was used Auto install script and I maybe some setting make problem)

This morning Everything back to work again after hard work. As a normal user I don’t know anything about code or programming, this is a chanllenge I am proud of myself.

And thank you very much for Your awesome plugin.
You save a lots of us!