Some of the apps on the toolbar will not open.

On keyboard SHIFT and Click the offending Application icon in the Dock ( Toolbar )

This is a Safe Launch process only for the Application.

If still not working Remove the icon from Dock ( Toolbar ) and follow previous advise.

One application is loaded Right Click the icon in Dock ( Toolbar ) and choose Keep in Dock ( Toolbar )

What is "Toolbar"? Do you mean the Dock, as P. Phillips assumed?

Which applications fail to launch?

Try this: click and hold one of those in the Dock, and choose Options->Show in Finder. Does it take you to the application, inside the Applications folder? No?

You can click and hold, and choose Options->Remove from Dock.

Then drag it from the Applications folder to the Dock.

By the way, you can launch applications, etc without ever touching the Dock - e.g. Command-Space, type Saf, press enter to launch Safari. Then command-tab to switch between open applications. I do not see the Dock all day...

Try to open them via the applications folder. This helps me when I have this problem on my iMac with Catalina.

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