Collect can't download forms after Central upgrade to v2026.x

Support
1

1. What is the issue? Please be detailed.

I have updated Central to 2026.2 from 2025.4 and got no errors/problems with the process. At the end the Central web UI is fully working.

version.txt reports

versions:
96f7d5e34c9ffba83c3248939070e0b3521c3103 (v2026.2.1-1-g96f7d5e)
 0000000000000000000000000000000000000000 client (v2026.2.1)
 bee93414a2215bd73d7f371113c6640c66d90c95 server (v2026.2.0)

The problem arises with Collect (2026.3.2), which is not able anymore to download/update the forms as the "progress bar" in the App never stops to move. On a Collect device that had already downloaded forms, trying to open a form result in (see the attached image).

WhatsApp Image 2026-08-02 at 11.47.07
WhatsApp Image 2026-08-02 at 11.47.071280Ɨ2772 159 KB

2. What steps can we take to reproduce this issue?

Upgrade Central to 2026.2 (or .1) from 2025.4

3. What have you tried to fix the issue?

Had a look at docker compose logs and seen nothing relevant.

Note: after the upgrade Enketo web forms stopped to work to, making necessary to use ODK web forms, is this expected?

2

Just one more note: I just tested a fresh install of ODK Central on a test server, and my forms work ok on Collect and as Enketo web forms, so it seems there is something wrong with the upgrade to 2026.*

3

Any suggestion how to troubleshoot this?

4

Hi @manghig

Have you tried force-closing ODK Collect? The issue may not necessarily be with ODK Central. It could be that ODK Collect is hanging while downloading form updates for some reason.

5

@Grzesiek2010 I completely cleaned Collect cache/storage and re-added the project. Same result.

6

Okay, so you might be right that the issue is related to ODK Central, but just to be 100% sure, could you try uninstalling ODK Collect and installing it again?

7

@Grzesiek2010 Done. No change unfortunately.

8

Do you have any customizations to Central? Or network configurations or firewalls that might be interfering?

9

@yanokwa none.

My Central instance is behind a reverse proxy, but I have no issues with it on 2025.4. Did something changed in this sense on 2026.*?

regards

10

Yes, we made a number of changes to the nginx config. How exactly is your upgraded install configured to work with the reverse proxy? And what happens if you put the fresh install you did behind the proxy?

11

Have you checked Central's logs after getting the download error on Collect?
Might show up as something there.

Another option you could possibly do is if Central has a verbose mode, restart it with it enabled and try downloading from Collect again.

12

@yanokwa @didotb My Central has custom ports configs... the moment I changed them to match a vanilla installation all seems to work. Worth adding a note in changelog? Thanks.

13

What specific ports are you using? Did you make the exact changes to .env and docker-compose.yml described in the using upstream SSL docs or do you have other changes?

14

As what @yanokwa has stated, custom port config has been in the docs, and it's been there for quite some time already I don't think it has to be added in the changelog as it wasn't the latest update that added it in.
I'm using a custom port and networking for my instance as well, while using cloudflare as both my reverse proxy and upstream ssl. Works quite well as expected since late 2023.

15

@yanokwa @didotb I had indeed the exact same port configuration as described here

and as I described in this ticket, the upgrade to 2026.x was not fully working. I changed the ports configs in .env and docker-composer.yml to match the ones that come in a fresh install (and no further changes) and it works (I had of course also to change accordingly the port config in my reverse proxy).

16

Filed an issue at https://github.com/getodk/central/issues/2122 so we can investigate further.