ERA5 downloads failing with AccessDenied error

Software and Tools API
1

I have been downloading ERA5 hourly data on pressure levels without an problems using the Python API. The last successful download was at about 09:38 UTC on 2026-06-20 when I downloaded data for 1994-03-31 15Z. Here are the last successfully downloaded file

-r--r--r--  1 k-bowman  admin   108M Jun 20 04:35 19940331T130000Z.ncd.CDS
-r--r--r--  1 k-bowman  admin   108M Jun 20 04:37 19940331T140000Z.ncd.CDS
-r--r--r--  1 k-bowman  admin   108M Jun 20 04:38 19940331T150000Z.ncd.CDS

Since that time I have been unable to download any additional files. The error message looks like this when I restart and try to download the 16Z file.

--- Processing 1994-03-31-16
2026-06-21 20:39:33,141 INFO Request ID is 0b2d7db2-3fb8-4347-ad33-7219038ade2d
2026-06-21 20:39:33,326 INFO status has been updated to accepted
2026-06-21 20:39:47,407 INFO status has been updated to running
2026-06-21 20:39:55,180 INFO status has been updated to successful
19e2617b2b21cba0ea1f8eb41b5e7fc5.nc: 0.00B [00:00, ?B/s]URL https://object-store.os-api.cci2.ecmwf.int:443/cci2-prod-cache-1/2026-06-20/19e2617b2b21cba0ea1f8eb41b5e7fc5.nc: <?xml version="1.0" encoding="UTF-8"?><Error><Code>AccessDenied</Code><Message></Message><BucketName>cci2-prod-cache-1</BucketName><RequestId>tx00000b7d0771a4f37c6e5-006a38926c-35d53ba7-default</RequestId><HostId>35d53ba7-default-default</HostId></Error>
Download failed: downloaded 0 byte(s) out of 113406420

The program then repeatedly re-tries the download and fails. Any idea what is going on?

Thanks, Ken Bowman

2

Hello,
i was running into the same issue and i’m not sure but it seems to be a bug on their side in relation with the caching of answer to optimize processing/answer speed.
The fix i found and that i will use while waiting for a fix is to add a parameter
‘nocache’: str(int(time.time())) to force their server to recalculate the answer for my request instead of using the cached precalculated answer.

Hope it helps

3

Thanks very much! That seems to have resolved this problem.

Ken