What does the "Unrecognized token openapi" error mean when using OpenAPI Generator with OpenAPI 3.0?

Question

I have written an API definition in the OpenAPI 3.0 format (https://swagger.io/docs/specification/basic-structure/). Now I'm trying to generate Java Spring objects as I was previously doing with a Swagger 2.0 definition and its associated Maven plugin.

So far, I have a basic API definition that begins with:

openapi: 3.0.0 info: title: Demo API description: This is a basic REST API implementing the [Open API Specification](https://en.wikipedia.org/wiki/OpenAPI_Specification). version: 0.0.1

In my pom.xml file I have added:

<dependency>
  <groupId>org.openapitools</groupId>
  <artifactId>openapi-generator-cli</artifactId>
  <version>3.3.3</version>
</dependency>

But when executing mvn install, I get this error:

com.fasterxml.jackson.core.JsonParseException: Unrecognized
     token 'openapi': was expecting ('true', 'false' or 'null')
     at [Source: definition\DEFINITION.yml; line: 1, column: 9]

Does anyone know where the problem is?

Is this the actual indentation of your definition.yml or just copy-paste formatting issues? The indentation is wrong - `info` must be on the same level as `openapi`. Paste your YAML into http://editor.swagger.io to make sure the syntax is correct. — Helen, Nov 19 '18 at 08:14
this is just a copy-paste. My yaml file is correct and no error is displayed when edited in Swagger editor. But it looks like "openapi" tag is not recognise. — vpa, Nov 20 '18 at 14:29
This is late and probably wrong, but maybe you should be using openapi-generator-maven-plugin instead of the CLI jar? — chrisinmtown, May 01 '19 at 18:47
I was getting same exception with openapi spec 3.0.0 and openapi-generator-maven-plugin version 5.10. Upgrading openapi-generator-maven-plugin to version 5.2.1 resolved the issue. — Akshay Joshi, Sep 29 '21 at 12:05

score 5 · Answer 1 · answered Dec 11 '21 at 17:47

After a lot for hit and try I found that issue was with my Swagger file. In that url was not a correct URL. It was something like /api (url without host domain).

OpenAPI generator could have given a better error message. Anyways placing some valid url, allowed me to generate the code.

score 1 · Answer 2 · answered Aug 23 '21 at 07:40

1

I had the same problem using io.swagger.codegen.v3.swagger-codegen-maven-plugin and windows (works fine on MacOS - so it couldn't have been a syntax issue).

Upgrading to most recent plugin version did fix the error (3.0.27 at the time of writing).

answered Aug 23 '21 at 07:40

Jonas

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score 1 · Answer 3 · answered Sep 22 '22 at 07:19

1

For me, it's the folder path that has space in it causing this error.

answered Sep 22 '22 at 07:19

blackr1234

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score 0 · Answer 4 · edited Jan 12 '22 at 09:42

0

I'm currently working on openapi-generator-maven-plugin to generate Java classes from an OpenAPI JSON schema.

The errors looks like a syntax problem. So first make sure your schema is syntactically correct and looks like this:

{
  "openapi": "3.0.0",
  "info": {
    "title": "Demo API",
    "description": "This is a basic REST API implementing the [Open API Specification](https://en.wikipedia.org/wiki/OpenAPI_Specification).",
    "version": "0.0.1"
  },
  # Schema definition goes here
}

edited Jan 12 '22 at 09:42

julemand101

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answered Nov 20 '18 at 15:34

R4FT3R

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Why should @vpa dumb down his perfectly valid YAML into JSON? – chrisinmtown May 01 '19 at 18:46
@chrisinmtown, It makes no logical sense for the user to do that. But since the exception indicates it is trying to use JSON parser to consume YAML input, I can see how this might workaround the issue. – Oliver Gondža Mar 01 '22 at 11:11

score 0 · Answer 5 · answered Jun 01 '21 at 14:00

I ran into the same issue (i need to mention that this occurs only on windows. The same code works fine under linux). While i do not have a "solution"n the workaround which works for me is to set:

validateSpec = false

So something like

generatorName = "typescript-angular"
validateSpec = false
inputSpec = "${myInputSpec}".toString()
outputDir = "${generatedCodeDir}".toString()

score 0 · Answer 6 · answered Nov 10 '21 at 17:20

I received a similar error using the CLI version of OpenAPI Generator. Based on this issue/comment, I believe any validation issue in a YAML spec will trigger the generator to assume the file is JSON.

At least that is what was happening with my file... sadly, I had to use a different tool to validate the YAML, and then OpenAPI Generator worked.

score 0 · Answer 7 · answered Aug 16 '22 at 08:16

Please change generator plugin and use https://openapi-generator.tech/docs/plugins, i.e.

<plugin>
   <groupId>org.openapitools</groupId>
   <artifactId>openapi-generator-maven-plugin</artifactId>
   <version>6.0.0</version>
   <executions>...</executions>
</plugin>

and my best bet is that it works flawless.

What does the "Unrecognized token openapi" error mean when using OpenAPI Generator with OpenAPI 3.0?

7 Answers7