org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException Caused by: java.lang.NullPointerException at java.lang.String.concat(String.java:1503) at com.sun.activation.registries.MailcapFile.parseLine(MailcapFile.java:235) at com.sun.activation.registries.MailcapFile.parse(MailcapFile.java:197) at com.sun.activation.registries.MailcapFile.createMailcapHash(MailcapFile.java:157) at com.sun.activation.registries.MailcapFile.<init>(MailcapFile.java:40) at javax.activation.MailcapCommandMap.loadFile(MailcapCommandMap.java:276) at javax.activation.MailcapCommandMap.<init>(MailcapCommandMap.java:128)
Curiously, this didn't occur until I started Mavenizing the project I was working on, though I was using the same version of JavaMail as before. The fix? Apparently it only happens if you're using Ubuntu. Open up ~/.mailcap and delete the -e at the top of the file.