Hi, I have the same issue un Production Mode.
I spent hundred hours programming the web app and now I can’t deploy it as production mode in the server of my client 
I followed all tutorials and recommendations but I can’t make work it. I’m just already losing my client.
This is the stacktrace on Tomcat 9:
Estado HTTP 500 – Internal Server Error
Tipo Informe de Excepción
mensaje com.vaadin.flow.server.ServiceException: java.lang.NullPointerException: source
Descripción El servidor encontró un error interno que hizo que no pudiera rellenar este requerimiento.
excepción
javax.servlet.ServletException: com.vaadin.flow.server.ServiceException: java.lang.NullPointerException: source
com.vaadin.flow.server.VaadinServlet.service(VaadinServlet.java:248)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
causa raíz
com.vaadin.flow.server.ServiceException: java.lang.NullPointerException: source
com.vaadin.flow.server.VaadinService.handleExceptionDuringRequest(VaadinService.java:1589)
com.vaadin.flow.server.VaadinService.handleRequest(VaadinService.java:1552)
com.vaadin.flow.server.VaadinServlet.service(VaadinServlet.java:246)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
causa raíz
java.lang.NullPointerException: source
java.util.Objects.requireNonNull(Objects.java:228)
java.util.Scanner.<init>(Scanner.java:578)
com.vaadin.flow.server.frontend.FrontendUtils.getStatsAssetsByChunkName(FrontendUtils.java:486)
com.vaadin.flow.server.BootstrapHandler$BootstrapPageBuilder.appendNpmBundle(BootstrapHandler.java:877)
com.vaadin.flow.server.BootstrapHandler$BootstrapPageBuilder.setupFrameworkLibraries(BootstrapHandler.java:859)
com.vaadin.flow.server.BootstrapHandler$BootstrapPageBuilder.setupDocumentHead(BootstrapHandler.java:742)
com.vaadin.flow.server.BootstrapHandler$BootstrapPageBuilder.getBootstrapPage(BootstrapHandler.java:517)
com.vaadin.flow.server.BootstrapHandler.synchronizedHandleRequest(BootstrapHandler.java:458)
com.vaadin.flow.server.SynchronizedRequestHandler.handleRequest(SynchronizedRequestHandler.java:40)
com.vaadin.flow.server.VaadinService.handleRequest(VaadinService.java:1540)
com.vaadin.flow.server.VaadinServlet.service(VaadinServlet.java:246)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
nota La traza completa de la causa de este error se encuentra en los archivos de registro del servidor.
Apache Tomcat/9.0.27
And this is my POM.xml:
<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.company</groupId>
<artifactId>gmesweb</artifactId>
<name>GmesWeb</name>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<failOnMissingWebXml>false</failOnMissingWebXml>
<vaadin.version>14.0.12</vaadin.version>
<jetty.version>9.4.15.v20190215</jetty.version>
</properties>
<pluginRepositories>
<pluginRepository>
<id>vaadin-prereleases</id>
<url>https://maven.vaadin.com/vaadin-prereleases</url>
</pluginRepository>
</pluginRepositories>
<repositories>
<repository>
<id>central</id>
<url>https://repo.maven.apache.org/maven2</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
<repository>
<id>vaadin-addons</id>
<url>https://maven.vaadin.com/vaadin-addons</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>com.vaadin</groupId>
<artifactId>vaadin-bom</artifactId>
<type>pom</type>
<scope>import</scope>
<version>${vaadin.version}</version>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>com.faendir.vaadin</groupId>
<artifactId>jfreechart-flow</artifactId>
<version>1.1.6</version>
</dependency>
<!-- https://mvnrepository.com/artifact/com.vaadin/vaadin-core -->
<dependency>
<groupId>com.vaadin</groupId>
<artifactId>vaadin-core</artifactId>
</dependency>
<!-- Added to provide logging output as Flow uses -->
<!-- the unbound SLF4J no-operation (NOP) logger implementation -->
<!-- https://mvnrepository.com/artifact/org.slf4j/slf4j-simple -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-simple</artifactId>
<version>1.7.25</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>commons-beanutils</groupId>
<artifactId>commons-beanutils</artifactId>
<version>1.9.2</version>
<type>jar</type>
</dependency>
<!-- AGREGADOS DIERGUI -->
<!-- https://mvnrepository.com/artifact/com.google.code.gson/gson -->
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.8.5</version>
</dependency>
<!-- https://mvnrepository.com/artifact/joda-time/joda-time -->
<dependency>
<groupId>joda-time</groupId>
<artifactId>joda-time</artifactId>
<version>2.10</version>
</dependency>
<!-- https://mvnrepository.com/artifact/commons-net/commons-net -->
<dependency>
<groupId>commons-net</groupId>
<artifactId>commons-net</artifactId>
<version>3.3</version>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.containers</groupId>
<artifactId>jersey-container-servlet</artifactId>
<version>2.8</version>
</dependency>
<!-- if you are using Jersey client specific features without the server side -->
<dependency>
<groupId>org.glassfish.jersey.core</groupId>
<artifactId>jersey-client</artifactId>
<version>2.8</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.apache.tomcat/tomcat-jdbc -->
<dependency>
<groupId>org.apache.tomcat</groupId>
<artifactId>tomcat-jdbc</artifactId>
<version>8.5.20</version>
</dependency>
<dependency>
<groupId>org.greenrobot</groupId>
<artifactId>eventbus</artifactId>
<version>3.1.1</version>
<type>jar</type>
</dependency>
<dependency>
<groupId>com.squareup.okhttp3</groupId>
<artifactId>okhttp</artifactId>
<version>3.11.0</version>
<type>jar</type>
</dependency>
<dependency>
<groupId>com.squareup.okhttp3</groupId>
<artifactId>logging-interceptor</artifactId>
<version>3.11.0</version>
<type>jar</type>
</dependency>
<dependency>
<groupId>com.sun.jersey</groupId>
<artifactId>jersey-bundle</artifactId>
<version>1.19.2</version>
<type>jar</type>
</dependency>
<dependency>
<groupId>org.vaadin.addons</groupId>
<artifactId>timer</artifactId>
<version>1.0.1</version>
</dependency>
<dependency>
<groupId>org.vaadin.tabs</groupId>
<artifactId>paged-tabs</artifactId>
<version>2.0.1</version>
<type>jar</type>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-annotations</artifactId>
<version>2.9.0</version>
<type>jar</type>
</dependency>
</dependencies>
<build>
<finalName>${project.artifactId}</finalName>
<plugins>
<plugin>
<groupId>com.github.eirslett</groupId>
<artifactId>frontend-maven-plugin</artifactId>
<!-- Use the latest released version:
https://repo1.maven.org/maven2/com/github/eirslett/frontend-maven-plugin/ -->
<version>1.8.0</version>
<executions>
<execution>
<!-- optional: you don't really need execution ids, but it looks nice in your build log. -->
<id>install node and npm</id>
<goals>
<goal>install-node-and-npm</goal>
</goals>
<!-- optional: default phase is "generate-resources" -->
<phase>generate-resources</phase>
</execution>
</executions>
<configuration>
<nodeVersion>v13.1.0</nodeVersion>
<!-- optional: with node version greater than 4.0.0 will use npm provided by node distribution -->
<!-- <npmVersion>2.15.9</npmVersion>-->
<!-- optional: where to download node and npm from. Defaults to https://nodejs.org/dist/ -->
<!-- <downloadRoot>http://myproxy.example.org/nodejs/</downloadRoot>-->
</configuration>
</plugin>
</plugins>
</build>
<profiles>
<profile>
<id>production-mode</id>
<properties>
<vaadin.productionMode>true</vaadin.productionMode>
</properties>
<dependencies>
<dependency>
<groupId>com.vaadin</groupId>
<artifactId>flow-server-production-mode</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>com.vaadin</groupId>
<artifactId>vaadin-maven-plugin</artifactId>
<version>${vaadin.version}</version>
<executions>
<execution>
<goals>
<goal>build-frontend</goal>
<goal>copy-production-files</goal>
<goal>package-for-production</goal>
</goals>
<!--
Fixme disabled by: https://vaadin.com/docs/v14/flow/production/tutorial-production-mode-basic.html
Triyng to start in dev mode
-->
<!--<phase>compile</phase>-->
</execution>
</executions>
</plugin>
</plugins>
</build>
</profile>
</profiles>
</project>
Please provide a solution.
Thanks for reading!