### Answer Based on community reports, 400 errors when updating agents can have several causes: **Post Call Analysis Limit**: If you're including post call analysis data, there's a limit of 100 fields [(1) ]() . Even if you're under the limit, this validation can sometimes trigger incorrectly . Try updating without the

post_call_analysis_data

field or set it to an empty array to test . **Payment/Billing Issues**: A 402 error (which can appear as 400 in some cases) indicates your trial has ended or a payment method is required [(2) ]() . Even if your account appears current, verify there are no billing holds on your organization . **Function/Tool Updates**: When updating function nodes specifically, CORS-related 400 errors have been reported, sometimes linked to underlying billing issues . **Browser Issues**: If updating through the UI, try switching to a different browser [(3) ]() . To troubleshoot, share your organization ID or agent ID with the Retell team for investigation [(1) ]() [(2) ]() .

​ To learn more, see the sources I considered: [[1] Can't update agent using Retell API (error: 400 Max post call analysis data count is 100)](https://discord.com/channels/1186424376300679209/1336119074752561192) [[2] Error code 400 When updating functions](https://discord.com/channels/1186424376300679209/1399721128796098670) [[3] Discord message from @fromtheedge on 2024-12-02](https://discord.com/channels/1186424376300679209/1186462578310910112/1313212803837857884) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.