Thanks for helping me with this problem.
I downloaded and installed Moodle 2.3+ (Build: 20120701) as a .zip file again as you suggested. I uploaded moodle-latest-23.zip to my dedicated server and unziped it there.
I can't find any link to list the roles and edit the permissions. In the Moodle Docs it says:
To edit a role:
Go to Settings > Site administration > Users > Permissions > Define roles.
Click the edit icon opposite the role you want to edit e.g. student.
On the edit role page, change permissions as required for each capability.
If I follow these instructions, I get the same coding error message and it doesn't list the permissions. SEE attached screenshot – edit_student_role.png
Some time ago I edited the Student permissions so they could not send messages to each other. I have changed my mind about this and need to change the messaging permissions. Now I can't find a way to edit the permissions.
In /Site Administration/Users/Permissions/Define roles/Student/ I clicked the EDIT tab but it doesn't list the permissions for the Student Role. SEE attached screenshot – edit_roles.png
I tried to reset the Student permissions to the defaults but it doesn't change the messaging permission either.
From /My home/My profile/Messages/ I see the users in my contact list. When I click on the user's name, it doesn't open the Message window to write a message. SEE attached screenshot – send_message.png. The "Send Message"
When I click a user's name in the Online Users block, it opens the user's profile but it doesn't show the "Send Message" button. SEE attached screenshot – Profile-send_message.png. The "Send Message"
Please let me know if you can suggest a solution to this problem.