Tomcat 7 - Servlet 3.0: Invalid byte tag in constant pool

Adding

metadata-complete="true" 

to your web.xml should sort the issue

<web-app version="3.0"
         xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
         metadata-complete="true">

This tells tomcat not to scan classes for annotations: http://www.tomcatexpert.com/blog/2011/10/12/how-use-fragments-and-annotations-configure-your-web-application

It may not be your issue, but mine was the same as this one -- an old version of com.ibm.icu:icu4j. I solved the problem by changing my build configuration to exclude the older transitive dependencies and explicitly depending upon the latest version (4.8).

Thanks James A Wilson for your answer - updating icu4j as you suggested worked for me and allows me to keep version="3.0" in my web.xml (which I prefer for the long run).

icu4j 2.6.1 was the version which did not work, upgrading to the NEXT version 3.4.4 will solve this problem. I did NOT go to the latest version of icu4j (49.1) because it is 4MB larger than version 3.4.4.

Here is a Maven configuration snippet to lock in your transitive dependency version (without adding an explicit dependency):

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>com.ibm.icu</groupId>
            <artifactId>icu4j</artifactId>
            <version>3.4.4</version>
        </dependency>
    </dependencies>
</dependencyManagement>

This turned out to be an incompatible jasper jar being included in the build, conflicting with the jasper.jar in tomcat 7.

I bumped into the same issue today. In my case, the dependency was coming via com.google.code.findbugs:annotations:jar:1.3.8. That means this library is only used at build time, to use annotations to turn off some findbug warnings. In this case, instead of changing the version, it is safe to just change the dependency scope and not take the library at runtime:

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>com.ibm.icu</groupId>
            <artifactId>icu4j</artifactId>
            <scope>provided</scope>
        </dependency>
        ....