Debugging steps for issues about Virtual User Generator (VuGen)

Debugging steps for issues about Virtual User Generator (VuGen)

If VuGen crashes intermediately or shows abnormal behavior, verify/try the following:

Try to login to the machine as a local administrator

Try to log in as a local administrator rather than user who is currently logged in. If this helps resolve the issue of VuGen crashing this would indicate that the cause of the problem is privileges of this particular user who is logged in. Check with your System Administrator on what privileges can/cannot be added to this user.

Make sure that there are sufficient Disk Space

Make sure that you have enough disk space available on the VuGen. If the machine does not have enough disk space, it can cause problem.

Try to run the VuGen’s batch files (for LoadRunner versions 8.x and below only)

Sometimes, DLLs can become unregistered or the registry can become corrupted to a point where a program’s DLLs cannot be found. The purpose of batch files is to reregister them into the system’s registry so that the programs can locate them. Use the following steps to do this:

1. Shut down the VuGen.

2. Navigate to the <LoadRunner>bin directory, and look for the file named register_vugen.bat

3. Create a duplicate copy of the file, in the same location.

4. Open up the duplicated file. In it, you should see several entries like the following:

regsvr32 /s webbrwsr.dll

Remove the "/s" from each of these statements, but leave a space between the "regsvr32" and the DLL name.

5. Save the changes.

6. Double click on the batch file to run it. You should get several pop-up messages similar to the following:

Note: You should not get any failure messages. If you do, then that DLL is the problem file. Try registering this from the command prompt:

Example: regsvr32 < LoadRunner >bin<DLL name>

If this does not work, try copying the DLL from the CD or ask support for the DLL to try registering it manually. Retry the same action that caused the error.

Ignore registration errors about files that do not exist in LoadRunner installation directory or installation CD. Batch files in some versions refer to obsolete file that are no longer needed but batch file still try to register them.

Try to recreate the VuGen’s initialization file

Sometimes, the initialization files can become corrupted (e.g. after a crashed). You will have problem in launching or using the VuGen after that. Use the following steps to do delete the initialization file so that a new copy will be created:

1. Shut the VuGen.

2. Navigate to the C:Winnt ( or C:Windows for Windows XP machine )

3. Delete the file named vugen.ini.

Check the temporary environment variables

Unlike the earlier window’s versions, Window 2000 and Window XP have the default environment set to c:Document and Settings<user-name>Local SettingsTemp instead of c:Windowstemp. This long path with a space can cause several problems on LoadRunner. To resolve the issue, change to a directory without empty spaces.

Verify if Hyper Threading is enabled

Verify if Hyper Threading is enabled. If so, you will need to disable it. LoadRunner does NOT support Intel Hyper-Threading technology. Hyper-Threading can be disabled in the BIOS. For more information, refer to

Verify the MDAC version

Make sure that you have MDAC 2.6 or higher installed. You can find the MDAC version on your machine by referring to the information on Microsoft Knowledge Base Article 301202 – HOW TO: Check for MDAC Version. You can download the latest MDAC version from MDAC Downloads


When programs crash, they leave the system in an unstable state. This can cause many other problems that seem to have no apparent reason for happening or has not happened before. When the system is rebooted, it resets the system into a more stable state. This should be done after any program crashes.

Verify the information in the event viewer

Sometimes, if a program crashes, it does not give any clues for what had happened. By using the Windows event viewer, it may be possible to find some clue as to what happened when the crash occurred. The event viewer can be launched from Start ® Programs ® Administrative Tools ® Event Viewer.

Verify if other programs are interfering with LoadRunner

To find out whether hooked DLLs are possibly causing a problem, you can use a third party utility call "Process Explorer." This utility has the ability to view the DLLs loaded by an application. It can be downloaded free of charge from the following link:

This can be used to see if LoadRunner loaded any other program’s DLLs. Use the following steps to do this:

1. Unzip the .zip file, which was downloaded from the above URL, into a directory where you wish to install Process Explorer.

2. Start the VuGen.

3. Run the Process Explorer (procexp.exe) from the directory into which you unzipped it (step a).


The top half of the screen list all the processes running on the machine. Click on menu ‘View | Lower Pane View’ and check dll’s and then the second half of the screen displays the list of DLLs used by the process which is highlighted in the top half of the screen.

5. Go to View->Select Columns->Dll. Check Path.

6. Select VuGen.exe (VuGen) from the top section of Process Explorer.

7. Search through the list to see if any other program’s DLLs are loaded. Normally, only DLLs from the <LoadRunner>bin directory and standard Microsoft directories are loaded. For example, if you see wbhook32.dll (McAfee VirusScan hooking DLL) loaded by LoadRunner, then you would want to shut down the anti-virus software.

Shut down all unnecessary processes

Some programs are designed to have certain DLLs "hook" or be loaded into another program’s memory space. Normally, this should not have any effect on the application itself. However, it can interfere with some programs and cause them to behave erratically or crash.

For such, it would be recommended to shut down all processes that are not necessary, regardless if they hook into LoadRunner or not. Any programs that run as an icon in the system tray or on the taskbar are the first candidates for termination. Also, you can look through the list of processes in the Task Manager (right-click on the taskbar and select "Task Manager"). Some processes are system processes, which may not be able to be shut off, but any processes that can be shut down should be.

Disable anti-virus software

It is known that anti-virus software is intrusive when they are set to look for viruses. However, in searching for viruses, the software can interfere with a program’s proper execution. This could cause problems and sometimes crashes. This is why, for debugging purposes, we would recommend turning off the anti-virus software.

The icon for the anti-virus software resides in the system tray (where the clock is located). Normally, you should be able to right-click on the icon and select "disable." However, some setups do not allow a user to turn off the anti-virus software. It is recommended to speak to a system administrator to get the anti-virus program disabled for a short period for debugging the problem.


In case that all the above steps fail, the only recourse left would be to try to uninstall LoadRunner. It is possible that either a previous version of LoadRunner was on the machine before the current installation or that the installation did not go properly although the installation did not give any errors. It is recommended that a full uninstall be done in this case. The following steps are for a full uninstall:

1. Make sure that, all running LoadRunner processes (including the Controller, VuGen, Analysis and the Remote Command Launcher (for 6.x) or the LoadRunner Agent Process/Service (for 7.x) are closed.

2. Backup any existing scripts that may have been saved in the LoadRunner installation folder (The scripts are sometimes saved in a ‘scripts’ subdirectory under the LoadRunner installation folder.).

3. Run the uninstall program from the LoadRunner program group (or) use the Windows add/remove programs from the Control Panel. If any prompt is given about removing shared files, remove all the shared dlls that are reported as no longer being in use. In the very rare instance this causes a problem for some other application it may be necessary to re-install that other app. This is not generally a problem because every application should have registered which DLLs it needs to run.

4. Reboot the machine after the Uninstall wizard is complete. This will complete the basic uninstall procedure.

5. Delete all LoadRunner Folders. (Including the ones in the startup menu for Remote Command Launcher (LoadRunner 6.x) or Agent Process (LoadRunner 7.x)

6. If the installation is LoadRunner 6.x then delete the Borland Folder (Usually in c:Borland or c:BDE).

7. Do a search for the following files and remove them from all locations — they will be replaced during the re-install.

a. wlrun.*

b. vugen.*

8. Bring up the registry editor: (Start à Run à regedit).

9. Delete the following keys:

a. Only for LoadRunner 6.x


b. If Load Runner is the only Mercury Interactive product on this machine, then delete



c. Else delete

HKEY_LOCAL_MACHINESOFTWAREMercury InteractiveLoadRunner.

HKEY_CURRENT_USERSOFTWAREMercury InteractiveLoadRunner.

10. Empty the Recycle-bin.

After you remove these items, you can re-install LoadRunner. Also, make sure that you do not have any anti-virus programs running while you are installing LoadRunner. That has been known to cause some problems with the installation of LoadRunner.

NOTE: Reinstallation should only be done for the following certain circumstances.

1. The crash only happens on a particular machine.

2. Some feature that was previously working is now crashing.

3. The above options were tried before hand.


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