In case when menu_link_attributes providing the class attribute it's not possible to save menu link translation.
1. Ensure that you have class attribute added to the configuratrion at /admin/config/menu_link_attributes/config
2. Create a menu link in English language, you can keep the cvalue for class attribute empty
3. Click on add a translation and try to save it, without any changes
4. You should be able to see the error: "Non-translatable fields can only be changed when updating the original language."
After deeper investigation I found that NestedArray::mergeDeep producing multiple array keys when saving translation and as a result EntityUntranslatableFieldsConstraintValidator throws validation error.
$existing_options = {array[1]}
attributes = {array[1]}
class = {array[1]}
0 = ""$menu_link_options = {array[1]}
attributes = {array[3]}
class = {array[1]}
0 = ""
data-separator = {int} 0
display-shop = {int} 0NestedArray::mergeDeep($existing_options, $menu_link_options)
attributes = {array[3]}
class = {array[2]}
0 = ""
1 = ""
data-separator = {int} 0
display-shop = {int} 0Replace NestedArray::mergeDeep($existing_options, $menu_link_options) with NestedArray::mergeDeepArray([$existing_options, $menu_link_options], TRUE) to preserve integer keys instead of appending them.
Active
1.5
Code
Thanks for posting a fix. Sadly, the patch from MR 29 has not resolved any of the 2 issues for me (NULL in Merge and untranslatable field).