# derby.stream.error.logBootTrace

The derby.stream.error.logBootTrace property specifies whether boot errors are written to the Derby log file.

This property helps in diagnosing double-booting problems. Typically, when two Java Virtual Machines (JVMs) or class loaders attempt to boot Derby, an error message like the following appears:

    ERROR XJ040: Failed to start database 'testdb' with class loader
    sun.misc.Launcher$AppClassLoader@481e481e, see the next exception for
    details.
    ERROR XSDB6: Another instance of Derby may have already booted the
    database C:\derby\testdb.

The message will also show the stack trace and class loader of the failed boot attempt. It is sometimes also useful to see the stack trace when the first successful boot attempt occurred. To see the stack trace of successful boots and shutdowns, set derby.stream.error.logBootTrace=true to trace the successful attempt. If you think that both attempts should be from the same class loader context, check also the class loader information for boot and shutdown attempts and make sure they all come from the same class loader context.

For more information, see "Double-booting system behavior" in Derby Developer's Guide.

## Default

False.

## Example

    derby.stream.error.logBootTrace=true

## Scope

system-wide

## Dynamic or static

This property is static; if you change it while Derby is running, the change does not take effect until you reboot.

Parent topic: Derby properties
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