Letter ё / е

You are hitting one of the biggest problems of modern Russian language, the never-ending battle between those who think that “ё” is irreplaceable and should always be written, and those who think that the letter should be omitted wherever possible.

As for now there are such formal rules:

1. Letter “ё” is mandatory written when omission of umlaut will lead to the wrong pronunciation of the word, for example, in proper nouns.

2. In all other situations it is up to author to decide when to use ё instead of е.

 Well, it depends. If we are talking about non-fiction literature, it’s often changed to “е” letter. But in fiction literature it depends on an author, an editor and a publishing house’ rules

Unfortunately, there are no grammar rules in the Russian printed press. No one is going to check the quality of these texts. They publish many grammatical, stylistic, and factual errors violating many rules (I can say this as a native speaker who reads news articles regularly)