Hi,
We noticed recent changes in the API vs. webform that started around Friday 24th of January 2025.
Having fixed the error of single netcdf files being downloaded as zipped files, we now face another issue that is massively breaking the downloading scripts using the CDS API to download hourly ERA5 Land data.
When launching a request using the API it fails as now the day parameter is forced to be an array of strings instead of a string even if only one day is requested. This is linked to the fact that now only single months can be requested, so we assume that all parameters that allow more than one selection have been changed to arrays whereas parameters allowing only single selection have been kept as strings.
But there is more, now there is a mismatch between the web request and the API request, as the API request works but the web request does not account for days and years and shows that the request is incomplete. But the request is run successfully.
It honestly makes no sense doing changes that might brake user’s requests without even notifying the users let alone the fact that the changes were pushed, most likely, on a Friday evening 
I attach 3 pictures with the API request, the webform request and the accepted request in my requests page.
