ImpressPages - Unable to add plugin / themes - impresspages

Question

I am new to Impress Pages. Using version 4.2.7 ( Installed 4.2.6 and upgraded from within the CMS). I have the following issues;
Tried to add the "PHP" plugin and got error message
"Plugin signature verification failed" . Plugin is NOT ADDED
I tried to add a new theme and got the error message Unknown error. Please see logs.
Where are these logs ? I have tried /var/log/apache2/error_log , etc.
Update 1: The log within the cms shows ;
2014-11-01 17:00:44 Cron.finished array(0) { } 2014-11-01 17:00:44
Cron.started array(7) { 'firstTimeThisYear' => bool(false)
'firstTimeThisMonth' => bool(false) 'firstTimeThisWeek' => bool(false)
'firstTimeThisDay' => bool(false) 'firstTimeThisHour' => bool(true)
'lastTime' => int(1414828943) 'test' => NULL }
I dont see anything related to plugins or themes ? Is there another log ?

Answer 1

The error says that the signature of the file can't be verified. There may be two reasons for that:
Your server is missing some encryption lib. But I guess current implementation should not require any additional libs.
The downloaded file is not what had to be downloaded. That could be due to DNS errors, network error, etc.
Which case it is can be told only by debugging. You can always download plugins from market.impresspages.org and install them manually.
If you want to debug, first place to look at is file/secure/tmp dir. You should find the downloaded plugin there. Have a look if you can unzip it. If you can un-zip, you have the problem number 1, otherwise 2.
Most likely your server couldn't download files from Internet.
You can