Support

As I have said before, this is a Joomla problem which can NOT be solved. I had reported all these problems to the pre-update checks four times in the year leading to Joomla 4's release and nobody was listening.

Joomla is stupidly using the update information to determine which versions of a software are compatible with which versions of Joomla.

Our software versions you mentioned (Admin Tools 6, Akeeba Backup 8, FOF 4, FEF 2) are compatible for installation with Joomla 4.0 and compatible merely for the purpose of upgrading your site with Joomla 4.1, 4.2 and 4.3 (when it will be released). However, there is no way to convey that.

We do not want to make these older versions of our software installable on Joomla 4.1 and later as we do not support using them on Joomla 4. While they will not break your Joomla 4 site they are non–native and they only run enough to let you upgrade to our Joomla 4 native software (Admin Tools 7, Akeeba Backup 9 etc).

If we lie in our update XML files you will have two problems instead of one:

• The extension will not be in the green part as there is a newer version compatible with Joomla 4. For example, Admin Tools 6 will be listed as non–compatible because Admin Tools 7 exists, it's a newer version and compatible with Joomla 4. This is the same problem you have.
• Akeeba Backup 8 users on Joomla 4.1 and later will keep being shown updates to Akeeba Backup 8 which cannot be installed because they are not installable on their site. They will flood us with questions as to why the updates don't work (despite the fact that the failed update prints a message to instead install Akeeba Backup 9).

As a result there is nothing we can realistically do about it. If you start thinking about it, the pre-update check only works for software by developers who are doing it WRONG: only publishing a small update to their Joomla 3 extension which is compatible with both Joomla 3.10 and Joomla 4.x at the same time. Come Joomla 5 they will face the same problem we are facing now. Their software will not work on Joomla 3, 4 and 5; they will have to have a different version for Joomla 3 and a different version for Joomla 4 and 5. Meanwhile our software will be compatible with both Joomla 4 and 5 and we will no longer have this problem.

The correct solution is for Joomla to completely remove the pre-update checks. They are unreliable. Not just for the reason I explained but also because they rely on package information in Joomla's database which does not exist if the user made use of the Discover method to install the sub-extensions of a package. Moreover, they falsely report all system and actionlog plugins as potentially harmful for the upgrade even though we have made sure this is not the case. Finally, the pre-update checks fail on servers with request rate limits, making perfectly compatible extensions appear as “incompatible”, just because Joomla failed to run its own (already problematic) code; I explained, reported and submitted a patch for this issue on January 2nd, 2022 but it's still not applied and as it looks like it will never be applied.

So here is my advice:

DO NOT TRUST THE JOOMLA PRE-UPDATE CHECKS. THEY ARE USELESS AT THE BEST OF TIMES, BLATANT LIES MOST OF THE TIME.

Now you know.