Can you describe the procedure used to update the site?

Sure.
First I tried to update from Components > Joomla Update component and after a few seconds page refreshed and nothing happened.
So then I copied the update link from the Joomla Update component and paste it to Extensions > Extension Manager > Install from URL and encountered with the error.

Hello,

I just tested this upgrade path locally and it worked fine without any issue.

Can you tell us more about your system information, found under Site -> Systems Information? Can you also paste the update link from the Joomla Update component?

Thank you for your support. Here is the details:
Update Link: https://github.com/joomla/joomla-cms/releases/download/3.3.6/Joomla_3.3.6-Stable-Update_Package.zip

Hosted on Siteground hosting.
All directory permissions are writable.
PHP Version: 5.4.17
Database Version: 5.5.31-30.3-log
Safe Mode Off
Open basedir None
Display Errors On
Short Open Tags On
File Uploads On
Magic Quotes Off
Register Globals Off
Output Buffering Off
Session Save Path /tmp
Session Auto Start 0
XML Enabled Yes
Zlib Enabled Yes
Native ZIP Enabled Yes
Disabled Functions None
Mbstring Enabled Yes
Iconv Available Yes

You're very welcome!

I don't see anything that seems to be a problem. I wonder if it may be a third-party extension causing it.

Since you are hosted by Siteground, have you contacted their support for assistance?

How many times have you tried the update? And, how long has this been going on? Have you tried testing this with a fresh install of 2.5.27 on the same server?

Maybe someone else who has experienced and solved this issue might be able to help as well.

I thought this is about Joomla but if you (or someone else) can not reproduce the issue then it's better to contact with Siteground support. Now I opened a ticket and will update this issue with details if they resolve it.

Thanks

Siteground detected the problem: it was Admintools' htaccess file which caused this issue.
Actually that's weird because I updated tens of site on the same server but this is the first time that problem occurd.
But renaming .htaccess to something else, updating and renaming it back to .htaccess worked and update is successful.

Excellent, glad that you were able to resolve the issue.

Does this mean Joomla-CMS on Github is now open for support requests that used to be referred to the forum?

No it doesn't, but potential bugs need to be properly investigated before dismissed.

Strange way to say yes!

Joomla_3.3.6-Stable-Update_Package.zip completly broke my website when i tried uploading via Extension Manager. I was using 2.5.27 and when I done that everything dissapeared. Now the website is gone and also the administrator interface is gone. They are both blank pages when I open them. Any ideeas? Thank you

This comment was created with the J!Tracker Application at issues.joomla.org/joomla-cms/4470.