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Recently, I needed to add swagger (openAPI) to my Spring boot app. However, with recent changes, it is almost impossible to use the infamous springfox implementation. When added the maven dependency to the project, I got errors that many others had:
2022-08-23 09:07:05.941 ERROR 265704 --- [ 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-5.3.20.jar:5.3.20] at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:54) ~[spring-context-5.3.20.jar:5.3.20] at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:356) ~[spring-context-5.3.20.jar:5.3.20] at java.base/java.lang.Iterable.forEach(Iterable.java:75) ~[na:na] at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:155) ~[spring-context-5.3.20.jar:5.3.20] at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:123) ~[spring-context-5.3.20.jar:5.3.20] at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:935) ~[spring-context-5.3.20.jar:5.3.20] at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:586) ~[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.binarycarpenter.license_server.LicenseServerApplication.main(LicenseServerApplication.java:11) ~[classes/: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$1(Comparator.java:473) ~[na:na] at java.base/java.util.TimSort.countRunAndMakeAscending(TimSort.java:355) ~[na:na] at java.base/java.util.TimSort.sort(TimSort.java:220) ~[na:na] at java.base/java.util.Arrays.sort(Arrays.java:1307) ~[na:na] at java.base/java.util.ArrayList.sort(ArrayList.java:1721) ~[na:na] at java.base/java.util.stream.SortedOps$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:510) ~[na:na] at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499) ~[na:na] at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921) ~[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:682) ~[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$1.accept(ReferencePipeline.java:197) ~[na:na] at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625) ~[na:na] at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509) ~[na:na] at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499) ~[na:na] at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921) ~[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:682) ~[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-5.3.20.jar:5.3.20] ... 14 common frames omitted
This is a known bug of the Spring fox open API implementation. Many people have tried to fix it and there are some workarounds. However, why settle for a workaround when you can have a much better, cleaner solution?
Add Swagger(OpenAPI) to Spring Boot application with Spring Doc
In my case, I completely removed spring fox’s dependencies. Instead, I used this:
<!-- https://mvnrepository.com/artifact/org.springdoc/springdoc-openapi-ui -->
<dependency>
<groupId>org.springdoc</groupId>
<artifactId>springdoc-openapi-ui</artifactId>
<version>1.6.11</version>
</dependency>
The current version at the time of this post is 1.6.11. However, you should check the official repository to get the latest versions.
After adding this dependency and removing all annotations required by spring fox previously, I got the open API (swagger) page up at http://myhost/myapp/swagger-ui.html
Actually, your app will redirect you to the other URL: http://myhost/myapp/swagger-ui/index.html
Support for Spring Boot 3
With the new Spring Boot version, using the version 1 of springdocs doesn’t work any more. Instead, you need to use the following dependencies in pom.xml
<dependency> <groupId>org.springdoc</groupId> <artifactId>springdoc-openapi-starter-webmvc-api</artifactId> <version>2.0.2</version> </dependency> <dependency> <groupId>org.springdoc</groupId> <artifactId>springdoc-openapi-starter-webmvc-ui</artifactId> <version>2.0.2</version> </dependency>
Then, your swagger URL would be accessible at the same endpoint swagger-ui/index.html
One word of caution regarding the error message saying “500 error v3/api-docs”. The cause could vary but in my case, it was a conflict with Spring data rest. Removing the spring data rest would resolve the problem. However, if you are heavily depend on Spring Data REST, you may need a different solution.
Conclusion
In this post, I’ve shown you how to quickly add open API (swagger) documentation to your spring boot application without using spring fox. This post is not to bash spring fox. That library has been one of the best solutions to add swagger to java web applications for a long time. However, with recent bugs, it’s better to use spring doc.
I build softwares that solve problems. I also love writing/documenting things I learn/want to learn.
Hi Dan,
I faced the same issue you’ve posted using Sprin-boot v3. I tried whatever was suggested, but none of the worked for me. I tried your suggestion, and it worked like a charm. Thanks !