In the CronExpression constructor, CronExpression calls buildExpression with the following line of code:

        buildExpression(cronExpression.toUpperCase(Locale.US));

However, in the readObject method, it has the following line of code:

            buildExpression(cronExpression);

I have a custom trigger with a cron trigger as a delegate. My cron expression looks like this:

19 15 10 4 Apr ?

When I create the cron trigger there is no problem. However, when I try to run the job, I get the following exception after the trigger has fired once:

org.quartz.JobPersistenceException: Unexpected runtime exception: Support for specifying both a day-of-week AND a day-of-month parameter is not implemented. [See nested exception: java.lang.UnsupportedOperationException: Support for specifying both a day-of-week AND a day-of-month parameter is not implemented.]

When the cron trigger is deserialized, the expression is not build correctly.