After upgradiing tot PHP 5.6 I become several errors:

Deprecated: Non-static method plgSystemYt::nameOfSJTemplate() should not be called statically, assuming $this from incompatible context in /home/tiebenvast/domains/tiebenvastgoed.nl/public_html/plugins/system/ytshortcodes/ytshortcodes.php on line 93

Deprecated: Non-static method JApplicationSite::getMenu() should not be called statically, assuming $this from incompatible context in /home/tiebenvast/domains/tiebenvastgoed.nl/public_html/plugins/system/yt/includes/site/lib/yt_template.php on line 116

Deprecated: Non-static method JApplicationCms::getMenu() should not be called statically, assuming $this from incompatible context in /home/tiebenvast/domains/tiebenvastgoed.nl/public_html/libraries/cms/application/site.php on line 272

Deprecated: Non-static method JApplicationSite::getMenu() should not be called statically, assuming $this from incompatible context in /home/tiebenvast/domains/tiebenvastgoed.nl/public_html/plugins/system/yt/includes/site/lib/yt_template.php on line 116

Deprecated: Non-static method JApplicationCms::getMenu() should not be called statically, assuming $this from incompatible context in /home/tiebenvast/domains/tiebenvastgoed.nl/public_html/libraries/cms/application/site.php on line 272

What can I do to solve this?

Regards,
Bram

Dear bramkip

Don't worry about these warnings, you can turn them off in Administrator -> Global configuration
-> Server and set Error reporting is None.

thanks