A child container failed during start java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Tomcat].StandardHost[localhost]]

Check all your Maven (or equivalent) dependencies and make sure that you - or most likely another dependency - are not pulling in a pre-3.1 version of the javax.servlet / servlet-api that may be taking precedence over what's in your Tomcat 8. If you've manually deployed, make sure you haven't manually copied any servlet-api JARs into Tomcat itself.


Below image you can see that old servlet API jar got added due to transitive dependency.

Solution:
Exclude servlet jar form dependency


Before:
<dependency>
<groupId>org.apache.velocity</groupId>
<artifactId>velocity-tools</artifactId>
<version>2.0</version>

</dependency>


After

<dependency>
<groupId>org.apache.velocity</groupId>
<artifactId>velocity-tools</artifactId>
<version>2.0</version>
<exclusions>
<exclusion>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
</exclusion>
</exclusions>

</dependency>