This is the problem. There is nothing in the log file. The upload starts (a 1Gbytes video), the Create/Update method (in the Controller) is not called, I see the progress bar running and then the page is reloaded .
For smaller files ( 230 MBytes or less), the upload starts and when the progress bar reaches 75%, the Update/Create method is trigged, including a delayed ActiveJob used to analyse the video (metadate[:duration] is not immediately available) and delete older video not used anymore (replaced by the one just uploaded) and then the progress bar continues to grow until it reaches the right hand side of the window (with the browser inspector, the progress bar could go up to 130%).
Started GET "/documents/23/edit" for 69.165.196.51 at 2022-08-05 11:06:56 -0400
...
Completed 200 OK in 30ms (Views: 25.5ms | ActiveRecord: 0.7ms | Allocations: 34667)
(filling the form ... 40 seconds)
Press the save button
-- wait 30 or 40 seconds **nothing happens in the console**
Started GET "/documents/23/edit" for 69.165.196.51 at 2022-08-05 11:08:35 -0400