Still no good.

I downloaded the file you made available.

Backed up the two original files.

Copied your file and overwrote two originals

<joomla_directory>/modules/mod_aridatatables/includes/kernel/Module/j16

and

<joomla_directory>/plugins/content/aridatatables/aridatatables/kernel/Module/j16

Double checked that these were the new and not old file. They both are the new one.

Login to the J3.9 back end and most screens are still white with the same error:

Fatal error: Cannot make static method Joomla\CMS\Helper\ModuleHelper::getModuleById() non static in class AriModuleHelper in /var/www/html/<mysite>/public_html/plugins/system/ariajaxdispatcher/ariajaxdispatcher/kernel/Module/j16/class.ModuleHelper.php on line 0

Note that the folder being referenced in the error is in ariajaxdispather directory tree and not the aridatables directory tree as referenced in your replacement instructions?

And replacing the file in:

/var/www/html/<mysite>/public_html/plugins/system/ariajaxdispatcher/ariajaxdispatcher/kernel/Module/j16/class.ModuleHelper.php

With the new one you provided seems to have worked - as far as I can tell functionality is restored to the back end of Joomla with v3.9.

Thanks!

Hello,

"Joomla\Filesystem\File::delete: Failed deleting inaccessible file index.html" error looks like a problem with file permissions on your server, not "ARI Data Tables" issue. BTW, you can upload the extension by FTP to your server, unzip it and install from directory. For this choose "Install from Folder" option on Joomla! installation page.

Regards,
ARI Soft

Attempting to do a proper update today.

Experienced J 3.9 failure on each of the 3 instances I have aridatatables installed on. Different servers.

Upload package files in the same way for each instance:

Error installing package.
Joomla\Filesystem\File::delete: Failed deleting inaccessible file index.html
Package Install: There was an error installing an extension: plg_system_ariajaxdispatcher.zip

Joomla files permissions are 664 and directories are 775. Confirmed. Owner is account and group is apache.

Attempted manual install from directory exactly as you describe on all three instances:

Uploaded zip and unzipped in joomla temp directory: ./tmp/aridatatables/

In Joomla clicked "Install from Folder"

Path to tmp folder is correct:

/var/www/nmcla/data/www/<site>/cms/tmp/aridatatables/

Click "Check and Install"

Results in:

Error installing package
Install path does not exist.
Package Install: There was an error installing an extension: mod_aridatatables.zip

So I cannot install manually either.

What next?

Changed the unzipped package file permissions to 777.

Install from folder now starts and then fails with the same error:

Warning
Joomla\Filesystem\File::delete: Failed deleting inaccessible file index.html
Package Install: There was an error installing an extension: plg_system_ariajaxdispatcher.zip

Error
Error installing package

Double checked file and directory permissions. They are as they should be: 664 and 775

Owership (confirmed) of all files and directories on site is the ftpuser and group is apache.

Side note - was able to update JCE and several other plugins, components, modules this morning via the Joomla upload updater with no problems - all three instances.

Could you provide a temporary access to your Joomla! backend and FTP access by email so we can investigate the problem?

Regards,
ARI Soft