It did not stay that way. It happen not only with the Chrome Browser. It also happend with Firefox and Opera. It happend on my PC with Windows 7 and on another PC with Windows 10.
If one is logged in without the keep me logged in option, one is bluntly logged out, if it happens. If one is logged in with the keep me logged in option, one is faced with the following message after klicking the save button:
Sorry! We could not process your edit due to a loss of session data. Please try again. If it still doesn't work, try logging out and logging back in.
I set $wgExtendedLoginCookieExpiration to null
(in MW 1.31 still on 180 * 86400
as default). No effect.
I contacted my provider and asked, if there may be some eager cron job is at work, which kicks sessions off. Nope.
I set $wgExtendedLoginCookieExpiration to null
(in MW 1.31 still on 180 * 86400
as default). Nothing.
I set $wgObjectCacheSessionExpiry to 24 * 3600
. Bingo! This does the trick! That really annoying and sometimes really frequently shown message as mentioned above has vanished!!!