'Springboot 2.6.0 / Spring fox 3 - Failed to start bean 'documentationPluginsBootstrapper'
I'm trying to initiate a Springboot project using Open Jdk 15, Springboot 2.6.0, Springfox 3. We are working on a project that replaced Netty as the webserver and used Jetty instead because we do not need a non-blocking environment.
In the code we depend primarily on Reactor API (Flux, Mono), so we can not remove org.springframework.boot:spring-boot-starter-webflux dependencies.
I replicated the problem that we have in a new project.: https://github.com/jvacaq/spring-fox.
I figured out that these lines in our build.gradle file are the origin of the problem.
compile("org.springframework.boot:spring-boot-starter-web") {
exclude module: "spring-boot-starter-tomcat"
}
compile("org.springframework.boot:spring-boot-starter-jetty")
Here is the build.gradle file:
plugins {
id 'org.springframework.boot' version '2.6.0'
id 'io.spring.dependency-management' version '1.0.11.RELEASE'
id 'java'
}
group = 'com.example'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '11'
repositories {
mavenCentral()
}
dependencies {
compile("org.springframework.boot:spring-boot-starter-web") {
exclude module: "spring-boot-starter-tomcat"
}
compile("org.springframework.boot:spring-boot-starter-jetty")
implementation 'org.springframework.boot:spring-boot-starter-webflux'
testImplementation 'org.springframework.boot:spring-boot-starter-test'
testImplementation 'io.projectreactor:reactor-test'
implementation "io.springfox:springfox-boot-starter:3.0.0"
}
test {
useJUnitPlatform()
}
I issued the command gradle clean bootrun. The result is this error:
gradle clean bootrun
> Task :bootRun FAILED
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.6.0)
2021-11-19 09:41:06.665 INFO 16666 --- [ main] c.e.springfox.SpringFoxApplication : Starting SpringFoxApplication using Java 15.0.2 on advance-Inspiron-5379 with PID 16666 (/home/advance/projects/spring-fox/build/classes/java/main started by advance in /home/advance/projects/spring-fox)
2021-11-19 09:41:06.666 INFO 16666 --- [ main] c.e.springfox.SpringFoxApplication : No active profile set, falling back to default profiles: default
2021-11-19 09:41:07.294 INFO 16666 --- [ main] org.eclipse.jetty.util.log : Logging initialized @1132ms to org.eclipse.jetty.util.log.Slf4jLog
2021-11-19 09:41:07.396 INFO 16666 --- [ main] o.s.b.w.e.j.JettyServletWebServerFactory : Server initialized with port: 8080
2021-11-19 09:41:07.398 INFO 16666 --- [ main] org.eclipse.jetty.server.Server : jetty-9.4.44.v20210927; built: 2021-09-27T23:02:44.612Z; git: 8da83308eeca865e495e53ef315a249d63ba9332; jvm 15.0.2+7-27
2021-11-19 09:41:07.417 INFO 16666 --- [ main] o.e.j.s.h.ContextHandler.application : Initializing Spring embedded WebApplicationContext
2021-11-19 09:41:07.417 INFO 16666 --- [ main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 713 ms
2021-11-19 09:41:07.474 INFO 16666 --- [ main] org.eclipse.jetty.server.session : DefaultSessionIdManager workerName=node0
2021-11-19 09:41:07.474 INFO 16666 --- [ main] org.eclipse.jetty.server.session : No SessionScavenger set, using defaults
2021-11-19 09:41:07.475 INFO 16666 --- [ main] org.eclipse.jetty.server.session : node0 Scavenging every 660000ms
2021-11-19 09:41:07.480 INFO 16666 --- [ main] o.e.jetty.server.handler.ContextHandler : Started o.s.b.w.e.j.JettyEmbeddedWebAppContext@6aa3bfc{application,/,[file:///tmp/jetty-docbase.8080.2024342829220941812/, jar:file:/home/advance/.gradle/caches/modules-2/files-2.1/io.springfox/springfox-swagger-ui/3.0.0/1e665fbe22148f7c36fa8a08e515a0047cd4390b/springfox-swagger-ui-3.0.0.jar!/META-INF/resources],AVAILABLE}
2021-11-19 09:41:07.480 INFO 16666 --- [ main] org.eclipse.jetty.server.Server : Started @1318ms
2021-11-19 09:41:07.920 INFO 16666 --- [ main] o.e.j.s.h.ContextHandler.application : Initializing Spring DispatcherServlet 'dispatcherServlet'
2021-11-19 09:41:07.920 INFO 16666 --- [ main] o.s.web.servlet.DispatcherServlet : Initializing Servlet 'dispatcherServlet'
2021-11-19 09:41:07.921 INFO 16666 --- [ main] o.s.web.servlet.DispatcherServlet : Completed initialization in 1 ms
2021-11-19 09:41:07.931 INFO 16666 --- [ main] o.e.jetty.server.AbstractConnector : Started ServerConnector@2643d762{HTTP/1.1, (http/1.1)}{0.0.0.0:8080}
2021-11-19 09:41:07.932 INFO 16666 --- [ main] o.s.b.web.embedded.jetty.JettyWebServer : Jetty started on port(s) 8080 (http/1.1) with context path '/'
2021-11-19 09:41:07.934 WARN 16666 --- [ main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.context.ApplicationContextException: Failed to start bean 'documentationPluginsBootstrapper'; nested exception is java.lang.NullPointerException: Cannot invoke "org.springframework.web.servlet.mvc.condition.PatternsRequestCondition.getPatterns()" because "this.condition" is null
2021-11-19 09:41:07.949 INFO 16666 --- [ main] o.e.jetty.server.AbstractConnector : Stopped ServerConnector@2643d762{HTTP/1.1, (http/1.1)}{0.0.0.0:8080}
2021-11-19 09:41:07.950 INFO 16666 --- [ main] org.eclipse.jetty.server.session : node0 Stopped scavenging
2021-11-19 09:41:07.951 INFO 16666 --- [ main] o.e.j.s.h.ContextHandler.application : Destroying Spring FrameworkServlet 'dispatcherServlet'
2021-11-19 09:41:07.951 INFO 16666 --- [ main] o.e.jetty.server.handler.ContextHandler : Stopped o.s.b.w.e.j.JettyEmbeddedWebAppContext@6aa3bfc{application,/,[file:///tmp/jetty-docbase.8080.2024342829220941812/, jar:file:/home/advance/.gradle/caches/modules-2/files-2.1/io.springfox/springfox-swagger-ui/3.0.0/1e665fbe22148f7c36fa8a08e515a0047cd4390b/springfox-swagger-ui-3.0.0.jar!/META-INF/resources],STOPPED}
2021-11-19 09:41:07.958 INFO 16666 --- [ main] ConditionEvaluationReportLoggingListener :
Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2021-11-19 09:41:07.970 ERROR 16666 --- [ main] o.s.boot.SpringApplication : Application run failed
org.springframework.context.ApplicationContextException: Failed to start bean 'documentationPluginsBootstrapper'; nested exception is java.lang.NullPointerException: Cannot invoke "org.springframework.web.servlet.mvc.condition.PatternsRequestCondition.getPatterns()" because "this.condition" is null
at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:181) ~[spring-context-5.3.13.jar:5.3.13]
at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:54) ~[spring-context-5.3.13.jar:5.3.13]
at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:356) ~[spring-context-5.3.13.jar:5.3.13]
at java.base/java.lang.Iterable.forEach(Iterable.java:75) ~[na:na]
at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:155) ~[spring-context-5.3.13.jar:5.3.13]
at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:123) ~[spring-context-5.3.13.jar:5.3.13]
at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:935) ~[spring-context-5.3.13.jar:5.3.13]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:586) ~[spring-context-5.3.13.jar:5.3.13]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145) ~[spring-boot-2.6.0.jar:2.6.0]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:730) ~[spring-boot-2.6.0.jar:2.6.0]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:412) ~[spring-boot-2.6.0.jar:2.6.0]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:302) ~[spring-boot-2.6.0.jar:2.6.0]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1301) ~[spring-boot-2.6.0.jar:2.6.0]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1290) ~[spring-boot-2.6.0.jar:2.6.0]
at com.example.springfox.SpringFoxApplication.main(SpringFoxApplication.java:10) ~[main/:na]
Caused by: java.lang.NullPointerException: Cannot invoke "org.springframework.web.servlet.mvc.condition.PatternsRequestCondition.getPatterns()" because "this.condition" is null
at springfox.documentation.spring.web.WebMvcPatternsRequestConditionWrapper.getPatterns(WebMvcPatternsRequestConditionWrapper.java:56) ~[springfox-spring-webmvc-3.0.0.jar:3.0.0]
at springfox.documentation.RequestHandler.sortedPaths(RequestHandler.java:113) ~[springfox-core-3.0.0.jar:3.0.0]
at springfox.documentation.spi.service.contexts.Orderings.lambda$byPatternsCondition$3(Orderings.java:89) ~[springfox-spi-3.0.0.jar:3.0.0]
at java.base/java.util.Comparator.lambda$comparing$77a9974f$1(Comparator.java:469) ~[na:na]
at java.base/java.util.TimSort.countRunAndMakeAscending(TimSort.java:355) ~[na:na]
at java.base/java.util.TimSort.sort(TimSort.java:220) ~[na:na]
at java.base/java.util.Arrays.sort(Arrays.java:1306) ~[na:na]
at java.base/java.util.ArrayList.sort(ArrayList.java:1721) ~[na:na]
at java.base/java.util.stream.SortedOps$RefSortingSink.end(SortedOps.java:392) ~[na:na]
at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:na]
at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:na]
at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:na]
at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:na]
at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:485) ~[na:na]
at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) ~[na:na]
at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913) ~[na:na]
at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:na]
at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:578) ~[na:na]
at springfox.documentation.spring.web.plugins.WebMvcRequestHandlerProvider.requestHandlers(WebMvcRequestHandlerProvider.java:81) ~[springfox-spring-webmvc-3.0.0.jar:3.0.0]
at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195) ~[na:na]
at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625) ~[na:na]
at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) ~[na:na]
at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) ~[na:na]
at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913) ~[na:na]
at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:na]
at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:578) ~[na:na]
at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.withDefaults(AbstractDocumentationPluginsBootstrapper.java:107) ~[springfox-spring-web-3.0.0.jar:3.0.0]
at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.buildContext(AbstractDocumentationPluginsBootstrapper.java:91) ~[springfox-spring-web-3.0.0.jar:3.0.0]
at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.bootstrapDocumentationPlugins(AbstractDocumentationPluginsBootstrapper.java:82) ~[springfox-spring-web-3.0.0.jar:3.0.0]
at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.start(DocumentationPluginsBootstrapper.java:100) ~[springfox-spring-web-3.0.0.jar:3.0.0]
at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:178) ~[spring-context-5.3.13.jar:5.3.13]
... 14 common frames omitted
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':bootRun'.
> Process 'command '/home/advance/.sdkman/candidates/java/15.0.2-open/bin/java'' finished with non-zero exit value 1
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
* Get more help at https://help.gradle.org
Deprecated Gradle features were used in this build, making it incompatible with Gradle 7.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/6.9.1/userguide/command_line_interface.html#sec:command_line_warnings
BUILD FAILED in 2s
5 actionable tasks: 5 executed
Does anyone have an idea how to solve it?
Solution 1:[1]
Consider migration to springdoc
Solution 2:[2]
This problem's caused by a bug in Springfox. It's making an assumption about how Spring MVC is set up that doesn't always hold true. Specifically, it's assuming that MVC's path matching will use the Ant-based path matcher and not the PathPattern-based matcher. PathPattern-based matching has been an option for some time now and is the default as of Spring Boot 2.6.
As described in Spring Boot 2.6's release notes, you can restore the configuration that Springfox assumes will be used by setting spring.mvc.pathmatch.matching-strategy to ant-path-matcher in your application.properties file. Note that this will only work if you are not using Spring Boot's Actuator. The Actuator always uses PathPattern-based parsing, irrespective of the configured matching-strategy. A change to Springfox will be required if you want to use it with the Actuator in Spring Boot 2.6 and later.
Solution 3:[3]
The workaround mentioned in the below issue comment seems to be working for people with spring actuator as well. Just changing the path matcher won't work for projects using actuator.
https://github.com/springfox/springfox/issues/3462#issuecomment-1010721223
- set
spring.mvc.pathmatch.matching-strategytoant_path_matcherinapplication.propertiesfile- add this bean:
@Bean
public WebMvcEndpointHandlerMapping webEndpointServletHandlerMapping(WebEndpointsSupplier webEndpointsSupplier, ServletEndpointsSupplier servletEndpointsSupplier, ControllerEndpointsSupplier controllerEndpointsSupplier, EndpointMediaTypes endpointMediaTypes, CorsEndpointProperties corsProperties, WebEndpointProperties webEndpointProperties, Environment environment) {
List<ExposableEndpoint<?>> allEndpoints = new ArrayList();
Collection<ExposableWebEndpoint> webEndpoints = webEndpointsSupplier.getEndpoints();
allEndpoints.addAll(webEndpoints);
allEndpoints.addAll(servletEndpointsSupplier.getEndpoints());
allEndpoints.addAll(controllerEndpointsSupplier.getEndpoints());
String basePath = webEndpointProperties.getBasePath();
EndpointMapping endpointMapping = new EndpointMapping(basePath);
boolean shouldRegisterLinksMapping = this.shouldRegisterLinksMapping(webEndpointProperties, environment, basePath);
return new WebMvcEndpointHandlerMapping(endpointMapping, webEndpoints, endpointMediaTypes, corsProperties.toCorsConfiguration(), new EndpointLinksResolver(allEndpoints, basePath), shouldRegisterLinksMapping, null);
}
private boolean shouldRegisterLinksMapping(WebEndpointProperties webEndpointProperties, Environment environment, String basePath) {
return webEndpointProperties.getDiscovery().isEnabled() && (StringUtils.hasText(basePath) || ManagementPortType.get(environment).equals(ManagementPortType.DIFFERENT));
}
Solution 4:[4]
Not a solution but ... I downgraded spring-boot-starter-parent version from 2.6.0 to 2.5.6 and It started to work.
Solution 5:[5]
I will complete what Anatoly mentioned about using sprindoc.
First add and load the springdoc to your build.gradle (or maven):
// build.gradle
implementation "org.springdoc:springdoc-openapi-ui:1.6.4"
Add OpenAPIDefinition annotation to your main class:
@SpringBootApplication
@OpenAPIDefinition
public class MyApplication {
public static void main(String[] args) {
SpringApplication.run(MyApplication.class, args);
}
}
Now you can go to {URI}/swagger-ui/index.html and it will work showing the swagger view.
Solution 6:[6]
Only adding @EnableWebMvc in main class should resolve the problem:
@EnableWebMvc
@SpringBootApplication
public class MyApp {
public static void main(String[] args) {
SpringApplication.run(MyApp.class);
}
}
Solution 7:[7]
The popular workaround overriding a definition of WebMvcEndpointHandlerMapping was not working for me in some environments with JDK 17, Boot+Actuator 2.6, Springfox 3.
This, however, is working for me everywhere I need it (local development and CloudFoundry containers):
@Bean
public WebMvcRequestHandlerProvider webMvcRequestHandlerProvider(Optional<ServletContext> servletContext, HandlerMethodResolver methodResolver, List<RequestMappingInfoHandlerMapping> handlerMappings) {
handlerMappings = handlerMappings.stream().filter(rh -> rh.getClass().getName().contains("RequestMapping")).toList();
return new WebMvcRequestHandlerProvider(servletContext, methodResolver, handlerMappings);
}
I wrote a little more about it on the GitHub thread.
Solution 8:[8]
Just if someone is having difficulties with this setup, here is my config which is setup for actuator and spring boot 2.6.6:
In my application.yaml:
swagger:
title: ^project.name^
description: ^project.description^
version: ^project.version^
termsOfServiceUrl: \#
contactName: Your name
contactUrl: \#
contactEmail: email
license: License of API
licenseUrl: \#
Make sure that in your pom.xml within <properties> you place:
<properties>
<resource.delimiter>^</resource.delimiter>
</properties>
The above is important for following config:
import lombok.Getter;
import lombok.Setter;
import org.springframework.boot.actuate.autoconfigure.endpoint.web.CorsEndpointProperties;
import org.springframework.boot.actuate.autoconfigure.endpoint.web.WebEndpointProperties;
import org.springframework.boot.actuate.autoconfigure.web.server.ManagementPortType;
import org.springframework.boot.actuate.endpoint.ExposableEndpoint;
import org.springframework.boot.actuate.endpoint.web.*;
import org.springframework.boot.actuate.endpoint.web.annotation.ControllerEndpointsSupplier;
import org.springframework.boot.actuate.endpoint.web.annotation.ServletEndpointsSupplier;
import org.springframework.boot.actuate.endpoint.web.servlet.WebMvcEndpointHandlerMapping;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;
import org.springframework.util.StringUtils;
import springfox.documentation.builders.PathSelectors;
import springfox.documentation.builders.RequestHandlerSelectors;
import springfox.documentation.service.ApiInfo;
import springfox.documentation.service.Contact;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spring.web.plugins.Docket;
import springfox.documentation.swagger2.annotations.EnableSwagger2;
@Getter
@Setter
@Configuration
@EnableSwagger2
@ConfigurationProperties(prefix = "swagger")
public class SwaggerFoxConfig {
private String title;
private String description;
private String version;
private String termsOfServiceUrl;
private String license;
private String licenseUrl;
private String contactName;
private String contactUrl;
private String contactEmail;
@Bean
public Docket apiDocket() {
return new Docket(DocumentationType.SWAGGER_2)
.useDefaultResponseMessages(false)
.select()
.apis(RequestHandlerSelectors.basePackage("path.to.base.package"))
.paths(PathSelectors.any())
.build()
.apiInfo(apiInfo());
}
private ApiInfo apiInfo() {
System.out.println(this.title);
return new ApiInfo(
this.title,
this.description,
this.version,
this.termsOfServiceUrl,
new Contact(this.contactName, this.contactUrl, this.contactEmail),
this.license,
this.licenseUrl,
Collections.emptyList());
}
@Bean
public WebMvcEndpointHandlerMapping webEndpointServletHandlerMapping(WebEndpointsSupplier webEndpointsSupplier, ServletEndpointsSupplier servletEndpointsSupplier, ControllerEndpointsSupplier controllerEndpointsSupplier, EndpointMediaTypes endpointMediaTypes, CorsEndpointProperties corsProperties, WebEndpointProperties webEndpointProperties, Environment environment) {
List<ExposableEndpoint<?>> allEndpoints = new ArrayList<>();
Collection<ExposableWebEndpoint> webEndpoints = webEndpointsSupplier.getEndpoints();
allEndpoints.addAll(webEndpoints);
allEndpoints.addAll(servletEndpointsSupplier.getEndpoints());
allEndpoints.addAll(controllerEndpointsSupplier.getEndpoints());
String basePath = webEndpointProperties.getBasePath();
EndpointMapping endpointMapping = new EndpointMapping(basePath);
boolean shouldRegisterLinksMapping = this.shouldRegisterLinksMapping(webEndpointProperties, environment, basePath);
return new WebMvcEndpointHandlerMapping(endpointMapping, webEndpoints, endpointMediaTypes, corsProperties.toCorsConfiguration(), new EndpointLinksResolver(allEndpoints, basePath), shouldRegisterLinksMapping, null);
}
private boolean shouldRegisterLinksMapping(WebEndpointProperties webEndpointProperties, Environment environment, String basePath) {
return webEndpointProperties.getDiscovery().isEnabled() && (StringUtils.hasText(basePath) || ManagementPortType.get(environment).equals(ManagementPortType.DIFFERENT));
}
}
Also in your .yaml or .properties have this setup:
spring:
mvc:
pathmatch:
matching-strategy: ANT_PATH_MATCHER
jpa:
bla..
springfox:
documentation:
swagger-ui:
baseUrl: scheduler-service
Back to pom.xml, have your Spring Boot version and Actuator setup:
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.6.6</version> <!-- lookup parent from repository -->
<relativePath/>
</parent>
...
<properties>
<spring.fox.version>3.0.4</spring.fox.version>
</properties>
<dependencies>
<dependency>
<groupId>org.thingsboard</groupId>
<artifactId>springfox-boot-starter</artifactId>
<version>${spring.fox.version}</version>
</dependency>
</dependencies>
You can find Swagger UI at:
http://localhost:8080/your-service-name-from-tag-'name'-in-pom-xml/swagger-ui/index.html
Solution 9:[9]
Remove anotations
@EnableSwagger2
@SpringBootApplication
@EnableSwagger2
public class Application {}
Solution 10:[10]
For me, it worked by adding @EnableSwagger2 annotation
@SpringBootApplication
@EnableSwagger2
public class Application {
Sources
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Source: Stack Overflow