REST API FAILING INTERMITTANTLY

Question

We are getting the following error when REST API is executed in retrieving data out of JIRA intermittantly:

Unable To Get List Of Jira Issues. Error During REST API Call. HTTP Reponse Code: 400

REST URL: https://lumen.atlassian.net//rest/api/3/search/jql

Input JSON: {"jql":"'CA PPM Task' = 'Yes' AND updated > '2026-03-25 11:00' AND issuetype = Capability ORDER BY subtasks","nextPageToken":null,"maxResults":"100","fields":["key","customfield_10255","customfield_10014","customfield_10061","customfield_10281","assignee","project","priority","status","id","created","statusCategory","summary","description","issuetype","updated","components"]}

REST Error Message: {"errorMessages":["Caught PSQLException for select /* called at com.atlassian.jira.issue.fields.FieldKeysManagerImpl.lambda$loadCfMapping$2(FieldKeysManagerImpl.java:79) */"CUSTOM_FIELD"."id", "CUSTOM_FIELD"."cfkey", "CUSTOM_FIELD"."customfieldtypekey"
from "public"."customfield" "CUSTOM_FIELD"
where "CUSTOM_FIELD"."cfkey" is not null and "CUSTOM_FIELD"."customfieldtypekey" is not null"]}

We have had no luck with a solution as to why the call is failing.

Duplicate Projects are created when process that uses this API call is executed as well as assignment of Projects to JIRA capabilities when in actual they have a Project already assigned from Clarity.

Any help would be appreciated.

Gor Greyan · Answer

Dear @Phillip Guardiola

Well, let me know if you have any questions.

Phillip Guardiola · Answer

Thanks. We will try your suggested solution.

Gor Greyan · Answer

Hi @Phillip Guardiola

I would treat this as two separate things: 
First, the error text points to Jira failing internally while resolving custom field mappings, which is why it looks intermittent and is something that I think Atlassian Support can investigate. Second, your request format is worth correcting, because Atlassian’s search API documents maxResults as an integer, and the newer /rest/api/3/search/jql pagination uses nextPageToken rather than the older body-based pagination pattern. Also worth validating the JQL itself directly in Jira and testing the same call without the custom fields, then adding them back one by one to see whether one field is triggering the backend failure.