Fatal Error on HTTP Request in Export (Works in Viewport)

Development Programming & Scripting Blueprint
, , , , , , ,
1

Hi everyone!
I’m experiencing an issue with my project in Unreal Engine 5.1, and I’m hoping someone here can help me figure it out.

Goal: I’m trying to send JSON data to a server using an HTTP POST request.
Works in Viewport: Everything works perfectly when running the project in the editor (Viewport).
Error in Export: When I export the project (in either Development or Shipping mode), the program crashes with a Fatal Error. The Fatal Error occurs only when I trigger the blueprint logic that calls the HTTP POST Request. In all other cases, the exported application runs without issues.

Blueprint Nodes Used:

  • I construct the JSON object using Set Field node.

  • I use the HTTP POST Request node to send the data.

  • I configure the headers with the Make Request Header node, setting Content-Type: application/json.

  • HTTP Plugin: The HTTP plugin is enabled and included in the packaging settings.

  • API Endpoint: The request is sent to a working HTTPS URL, which responds correctly when tested with a browser.

  • Test in Viewport: The URL and data work perfectly during Viewport tests, with no errors.

Error in Export: Fatal error! Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0x0000000000000020

What I’ve Tried So Far:

  1. Verified that the HTTP plugin and necessary contents are included in the Packaging Settings.
  2. Tested the API endpoint.
  3. Added debug logs to ensure the JSON and headers are constructed correctly. Everything appears fine in Viewport.

Question:

  • What could cause a Fatal Error that occurs only in Export but not in Viewport?
  • What can I check or configure to ensure the HTTP Request works correctly in Export?

Thank you so much in advance to anyone who can help! :blush:
If additional details or full logs are needed, I’m happy to share them.

2

If its only in build then allow all of private and public network when launching build for first time. if build has black screen and fatal error message or doesnt run then you can try disabling plugins that you dont use or that are not supported for example i used advanced steam sessions plugin and i didnt connect my project to steam so i disabled it and it worked. If it crashes on compilation then you need to make sure that result body isnt wildcard for example use print string to convert it in string. Hope it works!

3

Thank you for your message and advice, but unfortunately, I haven’t been able to resolve the issue! :frowning:

  • When launching the application for the first time after exporting it, I allowed access to private and public networks.
  • I don’t have any active plugins besides the HTTP Blueprint, as I’m working on a new project.
  • The project doesn’t crash during compilation but crashes when executing the HTTP POST Request node.