It has been more than 2 years ago when below issue was highlighted on this forum. By coincidence I hit this topic again and have finally figured out what its cause was.
It was about the appearance of a notice saying "Notice: Trying to get property of non-object in /home/xxx/public_html/administrator/components/com_users/models/user.php on line 111". The notice was displayed when the admin was trying to add or edit a user.

The reason was that Joomla! was looking for the parameters of the Joomla! user plug-in. This plug-in however had been disabled as part of the Login One! setup.
Joomla! version 3.7.4 and later only attempts to grab these parameters when the Joomla! user plug-in has been enabled. Therefore, an update to Joomla! version 3.7.4 or later resolves the issue.
I have included this information in the Login One! Trouble Shooting guide on www.innato.nl/13-tutorials/55-troublesho...gin-one-plug-in-j3-x

Login One! plug-in for J3 (all editions) is now PHP7 compatible. The J25 versions will follow.

ADDITIONAL NOTE: The J25 versions will NOT follow, because the Joomla! 2.5 core itself is not PHP 7 compatible. Therefore there is no point in making our J25 extensions PHP7 compatible.

Thanks Rob. I have already reported it to them and it was fixed a few days ago. I only posted it here in case it revealed any useful information for your extension (as one error seemed to be causing the other etc).

If you release any PHP 7.0 compatibility improvements and post a reply here, i would be happy to install it at first opportunity and check it out!

Regards,
George

Hi George,

I have learned more about PHP7 and am about to screen our Login One! plug-in for PHP 7 compatibility.
Your screendump which refers to an 'offlajn' error is an error that is thrown typically by PHP 7. The software is using a deprecated function naming convention that the software author should fix.

Hi George,
Thank you for your detailed info ref PHP 7.
I do not believe that the notice "Trying to get property of non-object in /home/xxx/public_html/administrator/components/com_users/models/user.php" has anything to do with the Login One! plug-in, because the Login One! plug-in is only involved in the logging-in (authentication) and logging-out process of users and not in the user data management like changing email addresses and passwords or so.
The Joomla! 3.5.1 update has appeared rather shortly after the Joomla! 3.5.0 release. Maybe there are some teething problems with the new J3.5 series.

I will analyse your information in detail and see whether something needs to be updated in the Login One! plug-in. For a standard operation (i.e. default error reporting) things seem to be perfectly OK, that's the good news.

Hi Rob,

Just to report back, i have tried version 1.9.5 (business) with PHP 7.0.4 (joomla 3.5.1) and have not discovered any errors using maximum reporting and chrome console. All functionality seems to be intact.

There is only a notice that appears when trying to edit a user's details in joomla:
Notice: Trying to get property of non-object in /home/xxx/public_html/administrator/components/com_users/models/user.php on line 111

I initially asked in Joomla forum in case they have seen it before, but after a short discussion they pointed out that the original joomla plugin is deactivated (i.e. replaced by login one in this case). Since then i have also checked this with version 1.9.6 which i just installed and i still see it. Could you see if there is something that needs updating?

Finally, i have been trying to test all my extensions with PHP 7.0.x and another extension (AJAX login module) had some "deprecated function" error messages which i reported to them and are currently being fixed. The reason i am mentioning this here is because one of their errors ended up causing one in Login One (i.e. they appear together or not at all, as far as i can tell). I am sending a screenshot just in case it proves to be useful.

Please let me know if you need any more information,

Thank you,
George