Undefined index: site

Since updating to 1.7 I get this message:


<div style='word-wrap: break-word; border: 3px solid red; padding:4px; 
width:70%; background-color:#FFFF96;'>
	    <strong>There is an error. Please report the message and full 
backtrace in the <a 
href='?module=Proxy&action=redirect&url=http://forum.piwik.org' 
target='_blank'>Piwik forums</a> (please do a Search first as it might 
have been reported already!).<br /><br/>
	    Notice:</strong> <i>Undefined index: site</i> in 
<b>/home/*my_user_name*/piwik/tmp/templates_c/%%9A^9A3^9A34FA06%%index.tpl.php</b> 
on line <b>49</b>
<br /><br />Backtrace --><div 
style="font-family:Courier;font-size:10pt">#0  Piwik_ErrorHandler(...) 
called at 
[/home/*my_user_name*/piwik/tmp/templates_c/%%9A^9A3^9A34FA06%%index.tpl.php:49]#1 
 include(...) called at 
[/home/*my_user_name*/piwik/libs/Smarty/Smarty.class.php:1263]#2  
Smarty->fetch(...) called at 
[/home/*my_user_name*/piwik/core/View.php:138]#3  Piwik_View->render(...) 
called at [/home/*my_user_name*/piwik/plugins/MultiSites/Controller.php:162]#4  
Piwik_MultiSites_Controller->getSitesInfo(...) called at 
[/home/*my_user_name*/piwik/plugins/MultiSites/Controller.php:36]#5  
Piwik_MultiSites_Controller->index(...) called at [:]#6  
call_user_func_array(...) called at 
[/home/*my_user_name*/piwik/core/FrontController.php:138]#7  
Piwik_FrontController->dispatch(...) called at 
[/home/*my_user_name*/piwik/index.php:53]</div><br />

Can someone help me with this?

Regards,
Dalabad

Delete all files in piwik/tmp/templates_c/* and try again?

Thanks for the tip. I removed all the files and startet the webpage again.
Now there is no error message on the page or in the log files.
But I cannot see any widgets.
As you can see on this image: http://prntscr.com/68ql0
When I click the “Dashbord”-Button in the menu I get this: http://prntscr.com/68qn9

But this is just text. I cannot click it.

How do I get the widgets back?

Please reupload all piwik files - some files haven’t been uploaded correctly?

I have uploaded all the files again, but nothing changed. There were no errors during the upload

and the delete all files in piwik/tmp/*

EDIT:
After deleting the browser cache, the tmp folder and uploading all files again. i got it back to work. thanks for you help

//OLD
The same. No change :frowning: