Cannot upgrade Photoshop Elements 2021

I have Photoshop Elements 2021 installed on my MacBook Air (15 months old) and my iMac (11 months old). Both have been running identical Mac OS, currently OS 12.3.1 Monterey.

There have been no problems with PSE 2021 on my MacBook Air.

However, on the iMac I keep getting a message that there’s a new update for Photoshop Elements. When I click on it, I get a message 

“There is no application set to open the URL auphd://updatesapCode=PSE&baseVersion=19.0&platform=osx10-64&skipUpdateInfo=true.”

Safari and Google Chrome can’t open it: “Address is invalid.”.

Adobe Help tells me to Update Adobe Application Manager using the link: 

Mac: https://www.adobe.com/support/downloads/detail.jsp?ftpID=4774

But neither Safari nor Google Chrome can open this page.

The only way out is to Force Quit from PSE 2021.

On a Chat with Adobe Help, I was advised to uninstall PSE 2021 and then reinstall it. That didn’t solve the problem.

Then they said that it was a problem with the Mac OS, and wait for an update. Well, there have been updates, and in any case there’s no problem on my MacBook Air.

In the end, I got a message from Adobe that this case is now closed.

I have got the impression that there’s a file missing somewhere in Adobe Preferences on my iMac. If so, how can I get it into place?