It was not a personal attack on you, it was an observation on you wanting to update/upgrade from 2.5 to 3.0 on a live site.
dont tell me i am not experieced because i had only a simple question ...
The answer to your question is not simple ... to update/upgrade from 2.5 to 3.0 is not a simple matter.
i am on the way with joomla since 1.xxx - so please dont tell me to try a xammp or something -
Then you should know not to update/upgrade between different series on a live site.
my question is only about the missing button - and again: why did joomla show me this function in 2.5.6. and not more in 2.5.8
Well one of your questions was
ca i upgrade a 2.5.8. to a 3.0.2 version ?
When I asked if it was a live site and you replied 'Yes' ... then I gave the answer which IMHO was correct.
If you are experienced and want to update/upgrade from 2.5.8 to 3.0.2 then I wish you luck.
As for 2.5.6 showing 3.0.x is available for update ... that should only happen if the Joomla update options have been changed. After using the 2.5.x to 2.5.8 patch then Joomla update component shows up to date ... until cache is cleared in Module manager >>> update tab. But even then the Joomla update options must have been changed in the first place.
I still maintain that anyone updating/upgrading ... from 2.5 to 3.0 on a live site ... is not as experienced as they think they are. Also, to change the settings on a live site to STS ... is not the act of an experienced user. Also would add that experience is learning from mistakes not the length of time doing something. If you are making the mistake of updating/upgrading 2.5 to 3.0 on a live site ... that speaks for itself.