Viewer Custom IFX throwing a java.lang.OutOfMemoryError

Technote (troubleshooting)


Custom Java IFX throwing a java.lang.OutOfMemoryError


After enabling the Viewer trigger file, c:\wpf.pel, you will see an error in the masqform.log or java.log:

    "Viewer : java.lang.OutOfMemoryError: Java heap space at ..."

During Viewer operation the Viewer may crash or show other errors.


The Java IFX requires more memory then the Viewer is allowing it to allocate.

Resolving the problem

To resolve the Out-of-Memory error you can increase the JVM heapsize. This is done by following these steps:

Navigate to the prefs.config of the Viewer (<Viewer installation location>\Prefs\prefs.config).
Open the prefs.config in a text editor and add these two lines.


Xmx is for the maximum heap and Xms is for the minimum. The default is 256. In order to confirm the change took affect you can query the memory size through the IFX.

This link will provide documentation that will assist in printing out the Java heap size.

Note: this is a client-side configuration and the change would have to be made for every system where the problem is experienced. As an organization you could standardize the configuration settings and then deploy the prefs.config file to each user's system, placing it in the directory specified above.

Related information

IBM Forms Support
IBM Forms Documentation

Document information

More support for:

IBM Forms
Forms product family

Software version:

3.0, 3.0.1, 3.5, 3.5.1,,, 4.0,,, 8.0,,, 8.0.1, 8.1

Operating system(s):


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Modified date:


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