1. What is the issue? Please be detailed.
Self-hosted.
versions:
3e9b78f4c7d1636982643585759c3d8a904904e3 (v2026.2.0-1-g3e9b78f)
0000000000000000000000000000000000000000 client (v2026.2.0)
bee93414a2215bd73d7f371113c6640c66d90c95 server (v2026.2.0)
After adding a new media field (image or video) to an existing form (by updating the form definition to a newer version), I am unable to upload media files (images or videos) when editing submissions created with an older version of the form definition (before the media file field was added). This is both via Webforms and Enketo. There is no issue uploading files on new or edited submissions created after the new definition was published.
2. What steps can we take to reproduce this issue?
I created a very simple sample forms that reproduces the issue:
- Created a new form with a definition containing a single text field (attached as test_one.xlsx)
- Using webforms, added a submission with random text
- Updated the form definition with test_two.xlsx. It adds an image field.
- Using webforms, added a second submission with text and image confirming upload works with new submissions.
- Using webforms, edited that second submission and picked another image file to replace the previous one, confirming that updating a submission created after the new form definition was uploaded works fine.
- Using webforms, edited the first submission and added an image. When saving, it failed with message:
Submission error
Your data was not fully submitted. Please press the “Try again” button to retry. If the error keeps happening, please contact the person who asked you to fill this Form or support@getodk.org.
After it fails, the image download icon appears in the submission list, but clicking on it returns:
{"message":"Could not find the resource you were looking for.","code":404.1}
With Enketo, the behavior is similar except that Enketo does not return an error message, as if it worked. But when downloading afterwards the same error occurs.
3. What have you tried to fix the issue?
I have checked that upload limits are high enough (I have increased them to 200 MB) and tested the error with a very small image file, confirming it is not an upload limit. ODK Central is running behind a reverse apache proxy. I have checked there a no restrictions there, which seems to be confirmed by the fact that second newer submission works fine both in creation and update.
I'd like to know if anyone can reproduce this problem with this simple test, so I know if it is related to a specific issue with my install or a more general problem. Thank you.
4. Upload any forms or screenshots you can share publicly below.
test_one.xlsx (13.5 KB)
test_two.xlsx (13.6 KB)