What I see here is a verification request that gets cancelled from the other side, but that doesn't sounds like what you're reporting? Rick: what were you doing when yo got the error and can you rageshake from AKYTREWRUB please?

I've got this exact same issue from riot-desktop 1.6.0 on MacOS. What is the equivalent of "rageshake" on MacOS?

Settings > Help & About > Submit debug logs

On Riot-Desktop, that is still in the initial setup. There is no UI except "Retry" and "Cancel".

You can open devtools (Cmd Shift I) and type mxSendRageshake("Message goes here", true); into the console to send a rageshake too

Cmd Shift I does nothing. Tried both left and right. (I'm new to Macs)

that's I as in "i" not l (L) btw

Yes I tried i.

Developer Tools is Alt-Cmd-I we just found out in the menu. Is that what you mean?

Yes, my bad, am not a Mac user. Sorry

Ok we just sent a report - message is "Unable to set up secret storage - to t3chguy".

ConnectionError: request failed: CORS request rejected: https://matrix-client.matrix.org/_matrix/client/unstable/keys/device_signing/upload
looks like a matrix.org issue/partial outage :( probably a timeout

Ok so we'll retry later. Thanks!

ConnectionError: request failed: CORS request rejected: https://matrix-client.matrix.org/_matrix/client/unstable/keys/device_signing/upload
looks like a matrix.org issue/partial outage :( probably a timeout

Exact same problem, linux, 17 hours later. Does not seem to make sense that outage is taking that long eh? Actually there is a few errors in sequence:
matrix-client.matrix.org/_matrix/client/unstable/keys/device_signing/upload:1 POST https://matrix-client.matrix.org/_matrix/client/unstable/keys/device_signing/upload 429

Access to XMLHttpRequest at 'https://matrix-client.matrix.org/_matrix/client/unstable/keys/device_signing/upload' from origin 'vector://vector' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

vendors~init.js:2 Resetting cross-signing keys failed, revert to previous keys ConnectionError: request failed: CORS request rejected: https://matrix-client.matrix.org/_matrix/client/unstable/keys/device_signing/upload

vendors~init.js:2 Error bootstrapping secret storage ConnectionError: request failed: CORS request rejected: https://matrix-client.matrix.org/_matrix/client/unstable/keys/device_signing/upload

edit: While doing this I was also setting up my android app, in the middle of it got some notifications and next time I retried it worked!

After many retries each failing the same way, we cancelled the encryption setup and restarted it via the Settings → Bootstrap cross signing dialog. We had to reenter the various passphrases again, got a new (different) recovery key to write down, and then the setup succeeded without any retry.

Which makes me think this wasn't really a timeout problem.