Blank/white Page At Front Of The Website After Saving Block In Layout

Store Builder Questions
1

While I am saving a HTML block in layaout page at admin said, I got error and the front of the page returned to blank/white page. I cleared all cache files in var/cache folder but I still get same error.

Here is the last error log when I got error:

[04-Feb-2016 22:17:48 UTC] PHP Notice:  unserialize(): Error at offset 7771 of 7780 bytes in /home/ydnemsa/public_html/app/Tygh/Session.php on line 204
[04-Feb-2016 22:17:48 UTC] PHP Notice:  unserialize(): Error at offset 0 of 634 bytes in /home/ydnemsa/public_html/app/Tygh/Session.php on line 204
[04-Feb-2016 22:17:48 UTC] PHP Notice:  unserialize(): Error at offset 4914 of 4923 bytes in /home/ydnemsa/public_html/app/Tygh/Session.php on line 204
[04-Feb-2016 22:17:48 UTC] PHP Notice:  unserialize(): Error at offset 0 of 71 bytes in /home/ydnemsa/public_html/app/Tygh/Session.php on line 204

Now I can not login to front of the page, but I can login to administrator side.

What is this problem and how to fix it?

I use MV 3.4.5

2

I realized that Blocks 0 blocks rendered while rendering blocks at frontpage.

I use Vivashop theme. When I change the theme to Responsive blocks are being rendered, but when I swtich to vivashop theme I see that no blocks rendered in DEBUG mode.

3

I have found and solved the problem. The problem was about license addon of vivashop. Uninstalled and reinstalled the license addon. Blocks are now OK.