An error is logged in the System Log for a Token Inline Hook execution with the following error summary: 

Could not deserialize inline hook response due to error at Line 1 Column <number>

• API Access Management
• OpenID Connect/OAuth application
• Token Inline Hook

If the Could not deserialize inline hook response error is received when Okta attempts to execute a Token Inline Hook configured on a Custom Authorization server, the most likely cause is that there is a syntax error in the hook's response back to Okta.

Ensure that the hook response is properly formatted JSON, with a list of commands returned, where each command in the list is an object containing both a "type" of command (either com.okta.identity.patch or com.okta.access.patch) and a list of "value", where each object in that list represents a specific operation to be performed on the specified token "type", with an "op", "path" to /claims/{{claimName}} or /token/lifetime/expiration and a "value" (that this claim/lifetime will be set to).

See example below:

{
  "commands": [
    {
      "type": "com.okta.identity.patch",
      "value": [
        {
          "op": "add",
          "path": "/claims/extPatientId",
          "value": "1234"
        }
      ]
    },
    {
      "type": "com.okta.access.patch",
      "value": [
        {
          "op": "add",
          "path": "/claims/external_guid",
          "value": "F0384685-F87D-474B-848D-2058AC5655A7"
        }
      ]
    }
  ]
}