OK... I was running Joomla 4.2.8... looks like 4.2.9 was available... well I installed that newer version then tried to update Admin Tools to 7.3.1... AND IT WORKED!
So I'm good for now... except that there was a warning message relating to .htaccess
.htaccess Update Concerning Setting the Content-Encoding Header
Since version 4.2.9
Before 4.2.9 the default htaccess.txt file contained erroneous code for appending the "Content-Encoding" HTTP header. This could result in double encoding errors when Joomla is installed in a subdirectory and both this directory and its parent directory contain an .htaccess file with this code. You should manually apply the necessary changes to any existing .htaccess file, as this file can not be updated automatically.
The old code:
Header append Content-Encoding gzip
The new code:
Header set Content-Encoding gzip
Since I use the .htaccess maker in my Admin Tools Pro... does this message apply to me?
Again... thanks.