Just got a little issue with some of my users today, when trying to open an email attachment in Lotus Notes, they get the error Unable To Invoke Program. Now, they can always just save the attachment and then open it through windows explorer, which is fine, but I would rather get a proper solution for this.

Knowing almost nothing about Lotus Notes does not help me I know but I think it may have something to do with the default file association, however my colleague tells me that Notes uses the windows file associations, which are working.

Any ideas anyone?

  • What was the attachment? – Simon O'Doherty May 25 '12 at 13:04
  • Was the attachment an .xlsx file by any chance? – kubanczyk May 25 '12 at 14:24
  • Yes it was an .xlsx, Also, I have had the same with .zip and .avi files. But usually its Excel Spreadsheets. – Ross Doughty May 25 '12 at 14:46
  • Was Notes "properly" installed or by some sort of "image/copy" mechanism? Or are you even using Citrix? – leyrer May 28 '12 at 11:57
  • No was installed properly using the setup. – Ross Doughty Jun 3 '12 at 9:51

Try deleting (backup beforehand) the Cache.NDK file (while notes client is not running).

Other then that, determine at what point did it stop working? If you recently migrated from an earlier version you can try running the NICE utility. Details are here.


Make sure you have backups of the important files in the Data folder before running it though.


This issue occurs when a single Notes client install is running the Multi-user Cleanup Service. This service, ntmulti.exe, should be installed only on Multi-user systems, not on single-user installations. On Notes client Single-User installs, check the system Services under Control Panel, Administrative Tools, Services, for "Multi-user Cleanup Service". If this service is started, stop it, and change the Startup Type from Automatic to Manual.

If the service ntmulti.exe is not present in the Services, and is not running as a process in Task Manager, even though the user observed the same symptoms. Re-running client setup to generate a new names.nsf, desktop6.ndk, and bookmark.nsf will resolve the issue


Lotus Notes error: Unable to invoke program

Error displayed when opening a Microsoft Excel file attachment from Notes client. This is an Excel issue which is fixed using the instructions below from Microsoft.

Excel Error: There was a problem sending the command to the program 1. Click the Microsoft Office Button, and then click Excel Options. 2. Click Advanced, and clear the Ignore other applications that use Dynamic Data Exchange (DDE) check box in the General area. 3. Click OK.

Then the file should open when double-clicked on.


The solutions involving Multi-user Cleanup Service, and the Ignore DDE checkbox, did not work for me. Try this; close all programs and go to Programs and Features in Control Panel. Run a repair on the MS Office package. This has worked for me in several instances in an office with about 60 Pc's. Spence

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.