Description of my issue:
NOTE: I made the issue go away by downgrading the site to PHP 7.0.16 from PHP 7.1.2. I thought I'd submit anyway.
I'm trying to update to Joomla 3.7. In my first attempt, the Akeeba Backup on update plugin was enabled. I got the following error nearly instantly when I initiated the Joomla 3.7 update (which initiated an Akeeba backup). The update does not proceed.
ERROR:
Invalid AJAX data:
<head/><br/>
<b>Deprecated</b>: Methods with the same name as their class will not be constructors in a future version of PHP; Akeeba_Services_JSON has a deprecated constructor in <b>/home/domainname/public_html/administrator/components/com_joomlaupdate/restore.php</b> on line <b>263</b><br/>
<br/>
<b>Deprecated</b>: Methods with the same name as their class will not be constructors in a future version of PHP; Akeeba_Services_JSON_Error has a deprecated constructor in <b>/home/domainname/public_html/administrator/components/com_joomlaupdate/restore.php</b> on line <b>925</b><br/>
I disabled the Backup on update plugin and I initiated the Joomla 3.7 upgrade again. What is odd is that the backup still initiates?
In this case, it goes all the way through completion but then I get the above message as soon as it appears to hand control back to the Joomla Updater.
Any thoughts? I tried the update on my local laptop and it went just fine. The above error happens in production. Note, I changed the path component to "domainname" for security reasons.
Also, the akeeba.backend.log file is zero bytes. It doesn't seem to get written?
I did run a successful backup manually before attempting the upgrade. It seems directly related to the Joomla 3.7.0 update attempt. The Joomla update never occurs.