# Other error messages

In addition to error messages that DITA Open Toolkit generates, you might also encounter error messages generated by Java or other tools.

## Out of Memory error

In some cases, you might receive a message stating the build has failed due to an `Out of Memory` error. Try the following approaches to resolve the problem:

1. Increase the memory available to Java.
2. Reduce memory consumption by setting the generate-debug-attributes option to `false`. This option is set in the lib/configuration.properties file. This will disable debug attribute generation (used to trace DITA-OT error messages back to source files) and will reduce memory consumption.
3. Set `dita.preprocess.reloadstylesheet` Ant property to `true`. This will allow the XSLT processor to release memory when converting multiple files.
4. Run the transformation again.

## UnsupportedClassVersionError

If you receive a `java.lang.UnsupportedClassVersionError` error message with an `Unsupported major.minor version` and a list of Java classes, make sure your system meets the minimum Java requirements as listed in the Release Notes and installation instructions.

## Unable to locate tools.jar

If a Java Runtime Environment (JRE) is used when building output via Ant, the `Unable to locate tools.jar` error may appear. This message is safe to ignore, since DITA-OT does not rely on any of the functions in this library. If a Java Development Kit (JDK) is also installed, setting the JAVA_HOME environment variable to the location of the JDK will prevent this message from appearing.