version 5.4.21 fixed it for me as well… now to fix all my websites that 5.4.21 broke 
My webhotel is using PHP 5.3.23, and they are not upgrading any time soon :S
Just got a mail today, they’ve pushed forward the PHP upgrade to 5.4 to Saturday here, so for me it’s probably going to solve itself, but this of course does not solve the code problem.
So you should as a minimum add a check for the upgrade that it’s minimum php 5.4, and then tell that the php is too old if it’s not.
Hey there,
another beta update is available and it may fixes the issue with PHP 5.3. Can you update your Piwik installation before updating PHP to verify whether it fixes the issue or not? As I mentioned we cannot reproduce the issue and we are interested in fixing it.
The visitors log still shows with empty rows, and clicking on the icon to produce the graph, I still see an error:
There is an error. Please report the message (Piwik 2.0-b5) and full backtrace in the Piwik forums (please do a Search first as it might have been reported already!).
Notice: Uninitialized string offset: 0 in /home/dkdbdk/analytics/plugins/CoreHome/DataTableRowAction/RowEvolution.php on line 91
Backtrace -->
#0 Piwik\Error::errorHandler(...) called at [/home/dkdbdk/analytics/plugins/CoreHome/DataTableRowAction/RowEvolution.php:91]
#1 Piwik\Plugins\CoreHome\DataTableRowAction\RowEvolution->__construct(...) called at [/home/dkdbdk/analytics/plugins/CoreHome/Controller.php:162]
#2 Piwik\Plugins\CoreHome\Controller->makeRowEvolution(...) called at [/home/dkdbdk/analytics/plugins/CoreHome/Controller.php:128]
#3 Piwik\Plugins\CoreHome\Controller->getRowEvolutionPopover(...) called at [:]
#4 call_user_func_array(...) called at [/home/dkdbdk/analytics/core/FrontController.php:114]
#5 Piwik\FrontController->dispatch(...) called at [/home/dkdbdk/analytics/index.php:56]
I can give you access to my stats site to test on, if you wish?
Coming right up…
Thank you so much! We identified the issue and were able to finally fix it. It works already for you and it will be fixed for other users in the next beta. It was related to a specific PHP setting.
Wow, fast work, very good to hear. I’m happy I could help out!