Are you using the following Find replace plugin which doesn’t seem compatible with the latest version of WordPress since it’s not updated from long time?
https://www.ads-software.com/plugins/find-replace/
We have tested on our test site using latest versions of Print Friendly and PDF Button & the above Find replace plugins along with default WordPress Twenty Fifteen theme but didn’t get any such messages.
Could you please share us the screenshot of the messages where you are getting it and tell us which versions of plugins, WordPress and PHP you are using?
To share screenshot you can use Google Drive, Dropbox, screencast.com, https://imgur.com/ or other image service. ??
We have tested it setting WP debug to true and got the following notices which are not same like you have shared.
Notice: WP_User->id was called with an argument that is deprecated since version 2.1! Use WP_User->ID instead. in wp-includes/functions.php on line 3495
Notice: has_cap was called with an argument that is deprecated since version 2.0! Usage of user levels by plugins and themes is deprecated. Use roles and capabilities instead. in /wp-includes/functions.php on line 3495
The above notices/warnings are generated by the Find replace plugin and not by Print Friendly and PDF Button plugin which you can confirm by temporary disabling the Print Friendly plugin.
You can also see in the following reply that other members are also facing the issue with that Find replace plugin.
https://www.ads-software.com/support/topic/polylang-redirects-to-blank-homepage?replies=10#post-5435529
From your shared messages it seems the issue is the non-static method plugin_findreplace::addPluginSubMenu() is being called statically.
To resolve this issue you can just try making the following non static methods as static methods by preceding them with static keyword as displayed below.
Find replace plugin files :
wp-content/plugins/find-replace/find_replace.php
wp-content/plugins/find-replace/mijnpress_plugin_framework.php
Before editing the methods are :
function addPluginSubMenu
function addPluginContent
After editing the methods will be :
static function addPluginSubMenu
static function addPluginContent
Note: You are making changes in the plugin file and these changes will be overwritten and lost when you update the plugin and you will have to make these changes again after plugin updation so it’s suggested to report this issue to the plugin author or if he is not responding then use alternate plugin or develop new one.
