This error message is generated when the process linked to the dashboard button is disabled.
To check if the process itself is enabled, follow these steps.
Firstly, find the name of the process linked to the button. Note the name of the board where the button is present.
Under Configuration, select Dashboard Link Controls.
Click the black arrow against the name of the Dashboard Link control noted at step 1.
Within the Menu Links tab, note the Item Name for the button.
In the Admin Tool, click Processes.
Find the process noted at step 1 and double-click it. It should show Yes in the Enabled tab (right-hand side of the window).
If this is enabled, then ensure that the process is added to the menu set so that the button can redirect the user to the respective process.
Once you have implemented the changes, the affected user may need to log out and log back in.