@Risk/DTS: "Could not attach to the already running copy of Microsoft Excel"

If Excel hangs, end any Excel.exe in Task Manager. If none, another add-in is delaying startup—disable startups, make @RISK an active add-in, or open Excel first.

Dec 11, 2025
Knowledge

Title

Answer

Applies to: All @Risk/DTS add-ins for Excel

Error:

"Could not attach to the already running copy of Microsoft Excel because it is invisible or unresponsive."

Background:

@RISK was able to launch Excel (or Excel was already running), but Excel is not answering messages from @RISK.

Causes and Solutions:

There is an instance of Excel running in the background that needs to be stopped.
1. Bring up Task Manager by selecting Ctrl+Shift+Esc.
2. Select the Processes tab.
3. Click the column heading Image Name to sort the processes.
4. Find Excel.exe in the list of processes. Highlight it and click End Process. When asked if you are sure you want to end the task, select Yes.
5. Close Task Manager by clicking the X at the top right.

NOTE: If this is an ongoing problem, you should investigate what is spawning these background processes of Excel. For example, some releases of certain third-party Excel add-ins create background processes of Excel and do not terminate properly.

2. If there was no background process of Excel running, @RISK was able to start Excel but Excel wouldn't answer messages from @RISK. This can happen when another Excel add-in or startup file takes too long to start, so that @RISK eventually gives up waiting for a response from Excel. You can fix this three ways:

Solution 1: Disable the other startups, them add them back one at a time to determine which one is the problem. See Find and Fix Startup Conflicts (Excel 2007–2013).
Solution 2: Make @RISK an active add-in.
- This will cause Excel to load @RISK when Excel is ready, instead of having @RISK load Excel and wait for a response from Excel. See Opening DTS Software Automatically Whenever Excel Opens
Solution 3: Start Excel.
- When Excel is open and you see "Ready" in the status bar, then launch @RISK (StatTools, PrecisionTree, ...) from the desktop icon, taskbar icon, or Start menu.
  - This has the disadvantage that you have to do it every time, but it doesn't require you to reconfigure Excel as Solutions 1 and 2 do.
  - TIP: in most versions of Windows, you can right-click the Excel icon in the Start menu and select Pin to Taskbar, so that the @RISK icon is always visible.

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@Risk/DTS: "Could not attach to the already running copy of Microsoft Excel"

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