Background
I work on an app that has many translations inside it.
I have the next English plural strings:
<plurals name="something">
<item quantity="one">added photo</item>
<item quantity="other">added %d photos</item>
</plurals>
and the French translation:
<plurals name="something">
<item quantity="one">a ajouté une photo</item>
<item quantity="other">a ajouté %d photos</item>
</plurals>
The problem
For both the French and Russian, I get the next warning:
The quantity 'one' matches more than one specific number in this locale, but the message did not include a formatting argument (such as %d). This is usually an internationalization error. See full issue explanation for more.
when choosing to show details , it says:
Thins is, I don't get what should be done to fix it, and if there is even a problem...
The question
What exactly should I do with those strings? What should I tell the translators?
I'm going to write an answer since this is quite an difficult explanation.
In various languages, nouns use the singular form if they end with 1. Refer to: http://www.unicode.org/cldr/charts/latest/supplemental/language_plural_rules.html
Explaining in English there are languages where it's correct to say "added 1 photo" as well as "added 101 photo". Notice the "photo". So this means that you should always add "%d" on one strings as well. Android will choose the best scenario to use. Which means that in English it will choose "other" for numbers > 1 and on other languages it will choose "one" for numbers ended in one.
Resuming, add to %d to your one string and should be fine. Also make sure your translators respect the plural rules for their language.
In French singular form is used when count is 0 or 1. In English singular form is used only when count is 1. 0 uses a plural form.
This is why you need to insert a placeholder (%d) in your French singular pattern.