SHOULD Send with 'application/json' content-type in notifications responses #1356

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1. YifengWong commented on Jan 4, 2026

   

   YifengWong

   on Jan 4, 2026

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   Java client codes in io.modelcontextprotocol.client.transport.HttpClientStreamableHttpTransport
2. mattzcarey

   self-assigned this

   on Jan 9, 2026
3. pcarleton

   closed this as completedin #1373on Jan 9, 2026
4. mattzcarey

   reopened this on Jan 15, 2026
5. mattzcarey commented on Jan 15, 2026

   

   mattzcarey

   on Jan 15, 2026

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   Reopening this since it should be fixed on the Java client. I don't play with Java too much but it seems like it may have been fixed in. modelcontextprotocol/java-sdk#589

   Or there is a similar issue open here modelcontextprotocol/java-sdk#396
6. felixweinberger

   added

   bugSomething isn't workingSomething isn't working

   needs confirmationNeeds confirmation that the PR is actually required or needed.Needs confirmation that the PR is actually required or needed.

   on Jan 28, 2026
7. felixweinberger commented on Jan 28, 2026

   

   felixweinberger

   on Jan 28, 2026

   Contributor

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   this is actually expected behavior per the spec — the server MUST return HTTP status code 202 Accepted with no body for notifications, so setting Content-Type: application/json would be semantically wrong.

   the fix should be on the java client side, which looks like it's been addressed in modelcontextprotocol/java-sdk#589. can you confirm if that fixes things for you?
8. felixweinberger

   closed this as not plannedon Jan 28, 2026