ODK Collect Not Sending Submissions? 6 Fixes
When ODK Collect won't send submissions, the cause is almost always one of six things: no usable connection, auto-send waiting for Wi-Fi, a revoked or misconfigured app user, a deleted or republished form on the server, an SSL certificate problem on self-hosted servers, or full device storage. Finalized interviews are safe on the device the whole time — fix the cause and they all go through.
If you are preparing a new field deployment, start with the ODK Collect offline workflow checklist and test one record before devices leave.
Work down this list in order; it is sorted by how often each one is the culprit.
1. The connection isn't actually usable
Mobile signal bars are not internet. Captive-portal Wi-Fi (hotel or office networks with a login page) connects but passes no data, and some networks block uploads while browsing works.
Fix: Open any website in the device browser first. If that fails, the problem is the network, not ODK. Switch to mobile data or a different network and retry.
2. Auto-send is waiting for a network you don't have
Collect's auto-send setting can be limited to Wi-Fi only — submissions then queue silently all day on mobile data and the team reports "nothing is sending."
Fix: In Collect, check Settings → Form management → Auto send. Set it to Wi-Fi and cellular for fieldwork, or send manually from Ready to send. Decide this before deployment and put it in enumerator training.
3. The app user was revoked or lost form access
An authentication error (401) or "access denied" on send means the device's app user no longer works: it was revoked in ODK Central, or its checkbox for this form was unticked under Form Access.
Fix: In ODK Central, confirm the app user exists and has the form checked under Form Access. If it was revoked, create a new app user and re-scan its QR code — the queued submissions then send normally.
4. The form changed on the server
If a form was deleted, retired, or replaced (rather than updated with a new version) on the server, pending submissions made against it can be rejected on upload.
Fix: Never delete a form that has unsent submissions in the field. Publish updates as new versions of the same form — ODK Central accepts submissions from older versions. If the form is already gone, restore or republish it with the same form ID, then retry sending.
Mid-fieldwork form edits are the classic self-inflicted outage. Update the form as a new version, confirm devices still send, and only then tell the team to update their downloaded form.
5. SSL certificate errors (self-hosted servers)
On self-hosted ODK Central, an expired or misconfigured SSL certificate makes every device fail with a generic connection error at once — usually exactly 90 days after setup, when the first Let's Encrypt certificate silently failed to renew.
Fix: Open the server URL in a desktop browser; an expired-certificate warning confirms it. Renew the certificate on the server. (On managed hosting, certificates renew automatically — whole-team send failures on a managed server are network or account issues instead.)
6. Device storage is full
Collect stores forms, photos, and audio locally. A device at 100% storage can fail to finalize or send, especially on media-heavy forms.
Fix: Check storage in Android settings and clear space (usually the camera roll). Then send the backlog in batches from Ready to send, oldest first.
Prevention: see the problem before the deadline
Every one of these failures looks identical from the office: submissions just stop arriving. The fix is monitoring the server side daily — expected versus received submissions per enumerator — so a silent device problem on day 2 doesn't become a 10-day data gap. DataSnap gives you that view live from your ODK server, and the data quality checklist covers the full daily routine.
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Frequently Asked Questions
Why is ODK Collect not sending my submissions?
The usual causes, in order: a network that connects but passes no data, auto-send restricted to Wi-Fi only, a revoked app user or removed form access, a form deleted or replaced on the server, an expired SSL certificate on self-hosted servers, or full device storage.
Are finalized submissions lost if they fail to send?
No. Finalized submissions stay safely stored on the device until they upload successfully. Fix the underlying problem — network, credentials, form, or storage — and send them from the Ready to send screen; nothing is lost while they wait.
What does the 401 or authentication error in ODK Collect mean?
The device's app user can no longer authenticate: it was revoked in ODK Central or lost access to the form. Verify the app user exists and has the form checked under Form Access, or create a new app user and re-scan its QR code.
Can I update a form while enumerators still have unsent submissions?
Yes, if you publish it as a new version of the same form — ODK Central accepts submissions from earlier versions. Never delete and re-create the form, because pending submissions against the deleted form can be rejected on upload.
Why did every device stop sending at the same time?
A simultaneous, team-wide failure points at the server, not the devices: most often an expired SSL certificate on self-hosted ODK Central, or a paused or down server. Open the server URL in a browser to confirm before touching any device.
How do I know submissions are arriving during fieldwork?
Check the server daily, not the devices: compare expected versus received submissions per enumerator in ODK Central or a monitoring dashboard like DataSnap. Silent sending failures are invisible in the field but obvious in a daily server-side count.
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