Spring Boot: Unable to start embedded Tomcat while using maven

2022-06-21 10:40:14.696  WARN 10965 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
2022-06-21 10:40:14.708  INFO 10965 --- [           main] ConditionEvaluationReportLoggingListener : 

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2022-06-21 10:40:14.796 ERROR 10965 --- [           main] o.s.boot.SpringApplication               : Application run failed

org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:165) ~[spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:577) ~[spring-context-5.3.20.jar:5.3.20]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:147) ~[spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:734) [spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:408) [spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:308) [spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1306) [spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1295) [spring-boot-2.7.0.jar:2.7.0]
    at com.javatechie.report.SpringBootJasperReportApplication.main(SpringBootJasperReportApplication.java:38) [classes/:na]
Caused by: org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
    at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:142) ~[spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.(TomcatWebServer.java:104) ~[spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getTomcatWebServer(TomcatServletWebServerFactory.java:479) ~[spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getWebServer(TomcatServletWebServerFactory.java:211) ~[spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.createWebServer(ServletWebServerApplicationContext.java:184) ~[spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:162) ~[spring-boot-2.7.0.jar:2.7.0]
    ... 8 common frames omitted
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'formContentFilter' defined in class path resource [org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.boot.web.servlet.filter.OrderedFormContentFilter]: Factory method 'formContentFilter' threw exception; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.fasterxml.jackson.datatype.jsr310.JavaTimeModule]: Constructor threw exception; nested exception is java.lang.NoClassDefFoundError: com/fasterxml/jackson/datatype/jsr310/ser/ZoneIdSerializer
    at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:658) ~[spring-beans-5.3.20.jar:5.3.20]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:486) ~[spring-beans-5.3.20.jar:5.3.20]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1352) ~[spring-beans-5.3.20.jar:5.3.20]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1195) ~[spring-beans-5.3.20.jar:5.3.20]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582) ~[spring-beans-5.3.20.jar:5.3.20]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.20.jar:5.3.20]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.20.jar:5.3.20]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.20.jar:5.3.20]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.20.jar:5.3.20]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:213) ~[spring-beans-5.3.20.jar:5.3.20]
    at org.springframework.boot.web.servlet.ServletContextInitializerBeans.getOrderedBeansOfType(ServletContextInitializerBeans.java:212) ~[spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.boot.web.servlet.ServletContextInitializerBeans.addAsRegistrationBean(ServletContextInitializerBeans.java:175) ~[spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.boot.web.servlet.ServletContextInitializerBeans.addAsRegistrationBean(ServletContextInitializerBeans.java:170) ~[spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.boot.web.servlet.ServletContextInitializerBeans.addAdaptableBeans(ServletContextInitializerBeans.java:155) ~[spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.boot.web.servlet.ServletContextInitializerBeans.(ServletContextInitializerBeans.java:87) ~[spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.getServletContextInitializerBeans(ServletWebServerApplicationContext.java:262) ~[spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.selfInitialize(ServletWebServerApplicationContext.java:236) ~[spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.boot.web.embedded.tomcat.TomcatStarter.onStartup(TomcatStarter.java:53) ~[spring-boot-2.7.0.jar:2.7.0]
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5219) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1396) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1386) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[na:1.8.0_191]
    at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:134) ~[na:1.8.0_191]
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:919) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:835) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1396) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1386) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[na:1.8.0_191]
    at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:134) ~[na:1.8.0_191]
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:919) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:263) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at org.apache.catalina.core.StandardService.startInternal(StandardService.java:432) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:927) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at org.apache.catalina.startup.Tomcat.start(Tomcat.java:486) ~[tomcat-embed-core-9.0.63.jar:9.0.63]
    at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:123) ~[spring-boot-2.7.0.jar:2.7.0]
    ... 13 common frames omitted
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.boot.web.servlet.filter.OrderedFormContentFilter]: Factory method 'formContentFilter' threw exception; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.fasterxml.jackson.datatype.jsr310.JavaTimeModule]: Constructor threw exception; nested exception is java.lang.NoClassDefFoundError: com/fasterxml/jackson/datatype/jsr310/ser/ZoneIdSerializer
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) ~[spring-beans-5.3.20.jar:5.3.20]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:653) ~[spring-beans-5.3.20.jar:5.3.20]
    ... 54 common frames omitted
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.fasterxml.jackson.datatype.jsr310.JavaTimeModule]: Constructor threw exception; nested exception is java.lang.NoClassDefFoundError: com/fasterxml/jackson/datatype/jsr310/ser/ZoneIdSerializer
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:224) ~[spring-beans-5.3.20.jar:5.3.20]
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:146) ~[spring-beans-5.3.20.jar:5.3.20]
    at org.springframework.http.converter.json.Jackson2ObjectMapperBuilder.registerWellKnownModulesIfAvailable(Jackson2ObjectMapperBuilder.java:832) ~[spring-web-5.3.20.jar:5.3.20]
    at org.springframework.http.converter.json.Jackson2ObjectMapperBuilder.configure(Jackson2ObjectMapperBuilder.java:691) ~[spring-web-5.3.20.jar:5.3.20]
    at org.springframework.http.converter.json.Jackson2ObjectMapperBuilder.build(Jackson2ObjectMapperBuilder.java:674) ~[spring-web-5.3.20.jar:5.3.20]
    at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.(MappingJackson2HttpMessageConverter.java:59) ~[spring-web-5.3.20.jar:5.3.20]
    at org.springframework.http.converter.support.AllEncompassingFormHttpMessageConverter.(AllEncompassingFormHttpMessageConverter.java:91) ~[spring-web-5.3.20.jar:5.3.20]
    at org.springframework.web.filter.FormContentFilter.(FormContentFilter.java:61) ~[spring-web-5.3.20.jar:5.3.20]
    at org.springframework.boot.web.servlet.filter.OrderedFormContentFilter.(OrderedFormContentFilter.java:29) ~[spring-boot-2.7.0.jar:2.7.0]
    at org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration.formContentFilter(WebMvcAutoConfiguration.java:177) ~[spring-boot-autoconfigure-2.7.0.jar:2.7.0]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_191]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_191]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_191]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_191]
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.3.20.jar:5.3.20]
    ... 55 common frames omitted
Caused by: java.lang.NoClassDefFoundError: com/fasterxml/jackson/datatype/jsr310/ser/ZoneIdSerializer
    at com.fasterxml.jackson.datatype.jsr310.JavaTimeModule.(JavaTimeModule.java:158) ~[jackson-datatype-jsr310-2.13.3.jar:2.13.3]
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_191]
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_191]
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_191]
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_191]
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:211) ~[spring-beans-5.3.20.jar:5.3.20]
    ... 69 common frames omitted

[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  03:42 min
[INFO] Finished at: 2022-06-21T10:40:14+06:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.7.0:run (default-cli) on project spring-boot-jasper-report: Application finished with exit code: 1 -> [Help 1]

This may happen while running:

mvn spring-boot:run 

if accidentally spring-boot-starter-parent dependency is missing from pom.xml:

Make sure Spring Boot Starter Parent dependency is included at the top of pom.xml. Not inside dependencies tag but, before build tag. Like:

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.4.0.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

<build>
   ...
</build>

<dependencies>
   ...
</dependencies>

which includes spring-boot-starter-tomcat dependency. Also make sure another process not using default tomcat port. If so, change server.port property inside application.properties.

Spring Boot : java.lang.NoClassDefFoundError: javax/mail/MessagingException

Exception in thread "main" java.lang.NoClassDefFoundError: javax/mail/MessagingException
Caused by: java.lang.ClassNotFoundException: javax.mail.MessagingException
        at java.net.URLClassLoader$1.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
Could not find the main class: MasterProcess.  Program will exit.
This may happen if you accedentaly add other javax.mail maven dependency into your pom.xml:

1. <dependency>
2. <groupId>javax.mail</groupId>
3. <artifactId>mail</artifactId>
4. <version>1.4</version>
5. </dependency>

but in Spring-Boot the actual dependency is:

1. <dependency>
2. <groupId>org.springframework.boot</groupId>
3. <artifactId>spring-boot-starter-mail</artifactId>
4. </dependency>

Goto: http://start.spring.io/

try creating maven project with javax mail dependency and examine the pom.xml. You will find some dependecies like this:

1. <?xml version="1.0" encoding="UTF-8"?>
2. <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
3.     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
4.     <modelVersion>4.0.0</modelVersion>
6.     <groupId>com.example</groupId>
7.     <artifactId>skeleton</artifactId>
8.     <version>0.0.1-SNAPSHOT</version>
9.     <packaging>jar</packaging>
11.     <name>demo</name>
12.     <description>Demo project for Spring Boot</description>
14.     <parent>
15.         <groupId>org.springframework.boot</groupId>
16.         <artifactId>spring-boot-starter-parent</artifactId>
17.         <version>1.4.0.RELEASE</version>
18.         <relativePath/> <!-- lookup parent from repository -->
19.     </parent>
21.     <properties>
22.         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
23.         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
24.         <java.version>1.8</java.version>
25.     </properties>
27.     <dependencies>
28.         <dependency>
29.             <groupId>org.springframework.boot</groupId>
30.             <artifactId>spring-boot-starter-mail</artifactId>
31.         </dependency>
33.         <dependency>
34.             <groupId>org.springframework.boot</groupId>
35.             <artifactId>spring-boot-starter-test</artifactId>
36.             <scope>test</scope>
37.         </dependency>
38.     </dependencies>
40.     <build>
41.         <plugins>
42.             <plugin>
43.                 <groupId>org.springframework.boot</groupId>
44.                 <artifactId>spring-boot-maven-plugin</artifactId>
45.             </plugin>
46.         </plugins>
47.     </build>
50. </project>

Spring Boot : Generate new maven project via Spring Boot

Spring Boot awsome CLI tool lets get start with new template project real quick :)

Go to http://start.spring.io/

Set group and package names,packaging(standalone(jar) or web(war)),project type(maven orgradle).

You can also select java version,language(java or groovy) and pre-add lots of dependencies(jpa,template engin,AOP and lote more :) ).

Click Generate project button and  project will be downloaded as zip :)

Doing it in shell/command prompt:
so that we can get it done via script:

1. #generate & download
2. spring init --build=maven --java-version=1.8 --dependencies=mail --packaging=jar skeleton.zip
3. #unzip
4. unzip skeleton.zip
5. #remove zip
6. rm -f skeleton.zip
7. #we have our project in current directory :)
8. cat pom.xml

look at the generated pom.xml:-

1. <?xml version="1.0" encoding="UTF-8"?>
2. <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
3.     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
4.     <modelVersion>4.0.0</modelVersion>
6.     <groupId>com.example</groupId>
7.     <artifactId>skeleton</artifactId>
8.     <version>0.0.1-SNAPSHOT</version>
9.     <packaging>jar</packaging>
11.     <name>demo</name>
12.     <description>Demo project for Spring Boot</description>
14.     <parent>
15.         <groupId>org.springframework.boot</groupId>
16.         <artifactId>spring-boot-starter-parent</artifactId>
17.         <version>1.4.0.RELEASE</version>
18.         <relativePath/> <!-- lookup parent from repository -->
19.     </parent>
21.     <properties>
22.         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
23.         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
24.         <java.version>1.8</java.version>
25.     </properties>
27.     <dependencies>
28.         <dependency>
29.             <groupId>org.springframework.boot</groupId>
30.             <artifactId>spring-boot-starter-mail</artifactId>
31.         </dependency>
33.         <dependency>
34.             <groupId>org.springframework.boot</groupId>
35.             <artifactId>spring-boot-starter-test</artifactId>
36.             <scope>test</scope>
37.         </dependency>
38.     </dependencies>
40.     <build>
41.         <plugins>
42.             <plugin>
43.                 <groupId>org.springframework.boot</groupId>
44.                 <artifactId>spring-boot-maven-plugin</artifactId>
45.             </plugin>
46.         </plugins>
47.     </build>
48. </project>

more examples here:-
http://docs.spring.io/spring-boot/docs/current/reference/html/cli-using-the-cli.html#cli-init

Batch(*.bat) Script : Install Spring-Boot CLI on Windows 7

1. mkdir C:\spring
2. cd C:\spring
3. C:
4. wget --no-check-certificate http://repo.spring.io/release/org/springframework/boot/spring-boot-cli/1.1.4.RELEASE/spring-boot-cli-1.1.4.RELEASE-bin.zip


REM "Latest version = 2.7.3.RELEASE . So, url http://repo.spring.io/release/org/springframework/boot/spring-boot-cli/2.7.3/spring-boot-cli-2.7.3-bin.zip should work."
5. unzip spring-boot-cli-1.1.4.RELEASE-bin
6. rm -f spring-boot-cli-1.1.4.RELEASE-bin.zip
7. cd spring-1.1.4.RELEASE
8. setx SPRING_HOME "%cd%"
9. refreshenv
10. cd bin
11. setx PATH "%PATH%;%cd%"
12. refreshenv
13. spring --version

Please make sure you have installed choletey and GNU unix-utils for Windows and go theough this article if you dont have any of above commands preinstalled :

http://mohiplanet.blogspot.com/2015/10/convert-windows-command-prompt-to-linux.html

JPA : Can not run ddl-auto=update with Spring Boot

Caused by: org.postgresql.util.PSQLException: ERROR: column i.indproc does not exist


This may happen while trying to update development db schema without loosing data and adding schema updates into development db:

1. spring.jpa.hibernate.ddl-auto=update

Problem is with Postgresql JDBC driver 9.1-901-1.jdbc4:

1. compile group: 'postgresql', name: 'postgresql', version: '9.1-901-1.jdbc4'

Upgrade it to latest version 42.2.5 in build.gradle:

1. compile group: 'org.postgresql', name: 'postgresql', version: '42.2.5'

Maven repository:
https://mvnrepository.com/artifact/org.postgresql/postgresql/42.2.5

maven:

<dependency>
    <groupId>org.postgresql</groupId>
    <artifactId>postgresql</artifactId>
    <version>42.2.5</version>
</dependency>