A field error is not shown in a translated page

[nimasmi]

If I translate then immediately ask to publish the home page in French, I get an error message at the top of the page, but no details about the specific error.

Steps to reproduce

• Create a new English language home page called home.
• Add a locale for French.
• Translate the home page into French.
• Publish the French home page.
• Observe an error message:

  New validation errors were found when publishing 'English homepage' in French. Please fix them or click publish again to ignore these translations for now.

• Change the French home page slug to home_fr.
• Publish again.

When the error is reported, the error message is only the red banner at the top of the admin, and there's no error styling on the tabs or the 'slug' field.

[kaedroho]

Thanks for reporting!

This is happening because errors are currently saved against translations, but in this case, it's failing on the original, untranslated slug value coming from the English page so there's nowhere to put the error.

A workaround for this would be to pass the slug into Wagtail's find_available_slug function which will check if the slug is available and append a -1, -2, etc to the end if not.

[TheBoroer]

Hey @kaedroho is it possible for me to see the exact validation error somehow (print it out in the server or browser console)?

I'm running into this exact issue with a page that's in translation sync mode (so not a separate page). I don't think the slug is the issue since we use SynchronizedField for the slug which should be fine with non-unique slugs (which works for every other page and even other pages of the same type site-wide).

override_translatable_fields = [
    SynchronizedField('slug', overridable=False),
]

Oddly enough, if i click stop translation sync on the page then publish it, it'll successfully publish... So I feel like, at least in my case, it's not the slug but some page field data it doesn't like.

I've already tried these things:

• made sure any page changes have been synced from the English/Primary locale. Publishing a different locale (via the translation UI) still fails with an unknown validation error.
• stop translation sync & publish. Then start translation sync again and try to publish = same validation error.
• deleted the translated page and expected all translation data to be deleted too but they apparently don't (#402).
• then tried to convert the translated page to an alias page since to try to wipe the translated page's data but translation strings are still prefilled when I click translate page. And the validation error still shows up when trying to publish.

The only thing I can think of that's left to try is to delete and re-create the pages (and translations) from scratch...but I'm trying to avoid that since it'll take quite a bit of time to re-enter everything).

Does anyone have any tips on how to troubleshoot this more or at least get a verbose output of the full error somehow?

[tutNichts]

Facing the same problem. Has somebody any idea on how to solve this?

[enzedonline]

May or may not be relevant -

I had this issue with a snippet with unique_together constraint:

unique_together = ('translation_key', 'locale'), ('locale', 'slug')

It would show the problem as described by OP, and throw an unhandled error when translating a page using linked to this model if a slug was repeated in the locale.

I needed to make a custom field type to take care of the validation:

class CategorySlugField(models.SlugField):
    def validate(self, value, instance, *args, **kwargs):
        super().validate(self, value)
        cat_type = instance.__class__
        found = cat_type.objects.filter(locale=instance.locale.id).filter(slug=instance.slug).exclude(pk=instance.pk)
        if found.count()>0:
            raise ValidationError(_(f"'{instance.slug}' is already in use by '{found.first()}'. Please select a unique slug."))