I’m really sorry for such a late reply. It’s good to find that our suggestion came of your help. It’s a nice gesture to engage in solving each other’s problems as it creates a learning atmosphere.
It seems your upgrade was successful, but it was not properly executed for which the links and the images were broken. May I know whether you’ve changed the path of your Moodledata directory or you have created a new Moodledata directory? When an image or pdf is uploaded in Moodle the data/files are stored in Moodle data folder with some hash codes. As a result of this, when an upgrade takes place Moodledata folder gets upgraded simultaneously including the path of the link.
I would suggest you to do the upgrade once more from 2.2.9 to any preferred version of 2.3. Please make sure that the same Moodledata directory associated with version 2.2.9 should be used. You’ll get Moodledata directory path from config.php file in your Moodle instance folder i.e., your_Moodle_folder/config.php
Also, I would suggest you, if you get the plug-in errors before you start upgrading, you’ve two options to deal with:
1.) Either you completely delete the plug-in folder from that path which is displayed on the screen; for example, in your screenshot you’ve got the error in mod_journal, in order to delete that folder, you meed to visit the path given below:
your_Moodle_folder/mod/journal, then delete the journal folder and reload the upgrade page.
(Note:- deleting the plug-in won’t upgrade the plug-in database further).
2.) Or you have to download the new plug-in which is compatible with the new upgrading Moodle version. After performing this, copy and replace the folder with the existing old plug-in folder.
I hope this resolves your issue. Please feel free to revert back for any further query.