You'll need a newer tcpdf if using the latest Imagick extension

Just a heads up for people using Imagick. If you’re on PHP 5.4 and are using the latest RC of the extension, then you’ll need to update the tcpdf library in order to be able to print PDF reports from Piwik. Email reports seem unaffected.

See the bug report: Cannot generate PDF reports on 1.8.3 (Imagick) · Issue #3322 · matomo-org/matomo · GitHub

and the fix:

for the error Strict Notice: Imagick::clone method is deprecated and it’s use should be avoided in www/libs/tcpdf/tcpdf.php on line 7880