# JSON-API error: mismatch with Ledger API

**URL:** <https://forum.canton.network/t/json-api-error-mismatch-with-ledger-api/7901>\
**Category:** App Development\
**Tags:** ledger-api\
**Created:** [April 19, 2025, 6:07am UTC](https://forum.canton.network/t/json-api-error-mismatch-with-ledger-api/7901 "2025-04-19T06:07:53Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Sindhusha](https://avatars.discourse-cdn.com/v4/letter/s/e95f7d/32.png) [@Sindhusha](https://forum.canton.network/u/Sindhusha)\
**Post date:** [April 19, 2025, 6:07am UTC](https://forum.canton.network/t/json-api-error-mismatch-with-ledger-api/7901/1 "2025-04-19T06:07:53Z")

</div>

Hello All,

I am trying to start a project and used the `simple-topography` example and uploaded a DAR file based on the contract we designed as per our requirements. I successfully created an instrument in the ledger, which is now stored.

Currently, I’m trying to fetch this data using Postman via the JSON-API. I configured the `json-api.conf` file to bind the Ledger API port 5011 to 7575 and started the service. However, when I trigger the request from Postman(All this while I am making sure canton is up and running) I encounter the following error:

```haskell
{
    "errors": [
        "Endpoints.ParticipantServerError: NOT_FOUND: LEDGER_ID_MISMATCH(11,a1b5ca2d): Ledger ID 'MyLedger' not found. Actual Ledger ID is 'participant1'."
    ],
    "status": 500
}

```

All files are as follows  
Json-api.conf

```haskell
{
  server {
    address = "localhost"
    port = 7575
  }
  ledger-api {
    address = "localhost"
    port = 5011
  }
  
}

```

simple-topology.conf

```haskell
canton {
  participants {
    participant1 {
      storage.type = memory
      admin-api.port = 5012
      ledger-api.port = 5011
    }
    participant2 {
      storage.type = memory
      admin-api.port = 5022
      ledger-api.port = 5021
    }
  }
  domains {
    mydomain {
      init.domain-parameters.protocol-version = 5
      storage.type = memory
      public-api.port = 5018
      admin-api.port = 5019
    }
  }
  // enable ledger_api commands for our getting started guide
  features.enable-testing-commands = yes
}

```

Kindly suggest me how to use JSON-api for fetching the contracts  
Thanks !

---

<div class="post-metadata">

**Author:** ![WallaceKelly](https://yyz2.discourse-cdn.com/flex034/user_avatar/forum.canton.network/wallacekelly/32/5046_2.png) [@WallaceKelly](https://forum.canton.network/u/WallaceKelly)\
**Post date:** [April 21, 2025, 2:49pm UTC](https://forum.canton.network/t/json-api-error-mismatch-with-ledger-api/7901/2 "2025-04-21T14:49:01Z")

</div>

@Sindhusha, which Canton version are you using? (The JSON API varies across versions.)

Are you passing a JWT to the JSON API? What is that token’s payload? For example, what is in the `aud:` field of your token? Is it “MyLedger”? Try changing that to “participant1”.