Can you explain the exact way to reproduce an issue please ?

Furthermore in sql installation field language is missing in table answers and questions, Shoud be there.

No : it's false answers and questions must not have a language field :
See https://github.com/LimeSurvey/LimeSurvey/blob/39990e8f8ed1accdc5505736967568397e3e8090/application/helpers/update/updatedb_helper.php#L2645-L2661
and https://github.com/LimeSurvey/LimeSurvey/blob/39990e8f8ed1accdc5505736967568397e3e8090/installer/create-database.php#L362-L378

Isn't it obvious? The sql query menitoned above causes an mysql error. Start e.g. phpmyadmin and enter with "lime_" as table prefix and an existing SurveyID assuming "en" as language

SELECT ls.id from lime_answer_l10ns ls JOIN lime_answers a on ls.aid=a.aid JOIN lime_questions q on a.qid=q.qid WHERE sid={$iSurveyID} AND language='en'

mysql throws an error "language is ambiguous"

You can trace the error in menu "General survey settings". Save settings and see the error 500 appearing on browser console.

PS.: In my report above "LEFT JOIN" should be replaced with "JOIN"

The tables answers and questions don't have a language field anymore.
It seems like your database is corrupted/not properly updated.
I strongly recommend to restart with a fresh database or use a databse backup from 3.x and retry the update using the latest version.

I have tested before posting the bug report:

Field language removed in answers: Ok
Field language removed in questions: limesurvey not starting

The reason:
In the source of e.g. 4.4.7 there are references to language of table questions
File: /application/models/Answer.php
Function: getAnswerQuery
Line 231 $query->where("{{questions}}.sid = :surveyid AND {{questions}}.qid = {{answers}}.qid AND {{questions}}.language = {{answers}}.language AND {{questions}}.language = :lang");

Perhaps I am wrong but I have done a safe update from v3 to v4 and fields language are still present.

To be in a safe harbour: Use qualfied field like ls.language in common_helper.php.

Field language removed in questions: limesurvey not starting

maybe you have plugins ?
Maybe send the error produced … i mean : activate debug, save error as HTML and send it here ...

It was removed from DB when update to version 400. Maybe you use a 4.0.0 release candidate ?

In the source of e.g. 4.4.7 there are references to language of table questions

@deprecated since 2018-02-05 its not working also (the language change)
https://github.com/LimeSurvey/LimeSurvey/blob/9cbf24f2c7001c61c5ba51e3bdfd8864407edcaa/application/models/Answer.php#L224

We can remove it :)

getAnswerQuery is deprecated and thus not updated.

Just removing the fields will not help, as the data is converted by the upgrade functions to the answers_i18n table.
As said, I strongly recommend to do a fresh install or redo the upgrade.

Closing because we cannot reproduce.