404 error occurs with RequestMapping(path="")

[koki8]

Used version

SpringBoot3.0.0 GA

Occurrence event

When I specify an empty string in Controller's RequestMapping (@RequestMappint(path="")) and access the root path,
The mapping doesn't work properly and I get 404. I could find the endpoint is created at startup, but the request never reaches the Controller.
This event does not occur in SpringBoot3.0.0 M3. It has occurred since M4.

Reproduction steps below

1. Create SampleController

@RestController
public class SampleController {

    @RequestMapping(path = "")
    public String demo(){
        return "test";
    }
}

2. Request to the following URL

• 「http://localhost:8080/」
• 「http://localhost:8080」

3. Check result

• Expected value
  The string of 「Test」 is displayed
  Status：200

• Actual
  Status：404

Supplement

• If any character is present in the @RequestMapping of the class or method, it will be successfully mapped.

• Confirmed for the following versions

SpringBoot version	Result
2.7.6	OK
3.0.0 M3	OK
3.0.0 M4	NG
3.0.0 GA	NG

[bclozel]

Closing as a duplicate of spring-projects/spring-framework#29625

[koki8]

@bclozel
It looks like the contents of this issue are not fixed.
I checked with SpringBoot 3.0.5 and the same issue occurred.

spring-projects/spring-framework#29625
404 occurred when using @GetMapping as well as the above Controller.

See below for reproduction procedure

1. create SampleController

@RestController
public class SampleController {

    @RequestMapping(path = "")
    public String demo(){
        return "test";
    }
}

2. request the following URL

• 「http://localhost:8080」
• 「http://localhost:8080/」

3. confirmation result

• Expected value
  • The string "test" is displayed.
  • Status：200
• Actual result
  • Status：404

Supplementation

Occurrence Conditions

case SpringBoot ver2.7.10

request	mapping	expected	actual	OK/NG
localhost	@RequestMapping	200	200	OK
localhost/	@RequestMapping	200	200	OK
localhost	@RequestMapping(path = "")	200	200	OK
localhost/	@RequestMapping(path = "")	200	200	OK
localhost	@RequestMapping(path = "/")	200	200	OK
localhost/	@RequestMapping(path = "/")	200	200	OK

case SpringBoot ver3.0.5

request	mapping	expected	actual	OK/NG
localhost	@RequestMapping	200	404	NG
localhost/	@RequestMapping	200	404	NG
localhost	@RequestMapping(path = "")	200	404	NG
localhost/	@RequestMapping(path = "")	200	404	NG
localhost	@RequestMapping(path = "/")	200	200	OK
localhost/	@RequestMapping(path = "/")	200	200	OK

※The same phenomenon occurs with @GetMapping

Versions confirmed to work

• Confirmed with the following version

SpringBoot version	Result
2.7.6	OK
2.7.10	OK
3.0.0 M3	OK
3.0.0 M4	NG
3.0.0 GA	NG
3.0.2	NG
3.0.3	NG
3.0.4	NG
3.0.5	NG

[bclozel]

@koki8 This issue is a duplicate of a Spring Framework issue that is not fixed yet. So this is expected.

[koki8]

@bclozel
spring-projects/spring-framework#29625
The duplicated SpringFramework issue is already closed, can you tell me which issue you are talking about?

[bclozel]

Apologies I thought it was not done yet. It looks like the enhancement is incomplete, I've opened spring-projects/spring-framework#30293 to fix that.