Mail.ru account for Domain (biz.mail.ru) returns 406 Not Acceptable on listing

The associated forum post URL from https://forum.rclone.org

None

What is the problem you are having with rclone?

Error 406 Not Acceptable when listing files/directories on a "Mail.ru for Domain" account.
I am using a verified App Password.
The account works correctly in the official Mail.ru client and Total Commander (via API v2).
Rclone fails to retrieve the file list.

What is your rclone version (output from rclone version)

rclone v1.73.1

• os/version: Microsoft Windows 10 Pro 22H2 22H2 (64 bit)
• os/kernel: 10.0.19045.6466 (x86_64)
• os/type: windows
• os/arch: amd64
• go/version: go1.25.7
• go/linking: static
• go/tags: cmount

Which OS you are using and how many bits (e.g. Windows 7, 64 bit)

Microsoft Windows 10 Pro 22H2 22H2 (64 bit)

Which cloud storage system are you using? (e.g. Google Drive)

Mail.ru

The command you were trying to run (e.g. rclone copy /tmp remote:tmp)

rclone -vv --dump headers --dump bodies lsd mailru:

A log from the command with the -vv flag (e.g. output from rclone -vv copy /tmp remote:tmp)

C:\Install\rclone-v1.73.1-windows-amd64>rclone -vv --dump headers --dump bodies lsd mailru:
2026/02/25 18:10:30 NOTICE: Automatically setting -vv as --dump is enabled
2026/02/25 18:10:30 DEBUG : rclone: Version "v1.73.1" starting with parameters ["rclone" "-vv" "--dump" "headers" "--dump" "bodies" "lsd" "mailru:"]
2026/02/25 18:10:30 DEBUG : Creating backend with remote "mailru:"
2026/02/25 18:10:30 DEBUG : Using config file from "C:\Users\admin\AppData\Roaming\rclone\rclone.conf"
2026/02/25 18:10:30 DEBUG : You have specified to dump information. Please be noted that the Accept-Encoding as shown may not be correct in the request and the response may not show Content-Encoding if the go standard libraries auto gzip encoding was in effect. In this case the body of the request will be gunzipped before showing it.
2026/02/25 18:10:30 DEBUG : >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
2026/02/25 18:10:30 DEBUG : HTTP REQUEST (req 0xc0004a4b40)
2026/02/25 18:10:30 DEBUG : GET /api/m1/file?access_token=cdafa903f9a271eb8c679d64ea5f704e512c1b9b3736383&home=&limit=2147483647&offset=0 HTTP/1.1
Host: cloud.mail.ru
User-Agent: rclone/v1.73.1
Accept: /
Accept-Encoding: gzip

2026/02/25 18:10:30 DEBUG : >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
2026/02/25 18:10:30 DEBUG : <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
2026/02/25 18:10:30 DEBUG : HTTP RESPONSE (req 0xc0004a4b40)
2026/02/25 18:10:30 DEBUG : HTTP/2.0 406 Not Acceptable
Content-Length: 100
Cache-Control: no-store, no-cache, must-revalidate
Content-Security-Policy: frame-ancestors 'self' https://myteam.mail.ru https://webim.internal.myteam.mail.ru https://app.workspace.vk.ru; report-uri https://cspreport.mail.ru/cloud?disposition=enforce&rev=cloud_26.10.23;
Content-Type: application/json; charset=utf-8
Date: Wed, 25 Feb 2026 15:10:30 GMT
Pragma: no-cache
Server: nginx
X-Email: support@glovertor.com
X-From: lightning_k8s
X-Host: cld-front-ext3.q
X-Page-Id:
X-Req-Id: e62462127b6ae837a7cf231245617cc2
X-Server: lightning
X-Timestamp: 1772032230
X-Timing: 0.0181381702423096
X-Ua-Compatible: IE=Edge
X-Upstream-Time: -

{"email":"support@glovertor.com","body":{"error":"NOT/ACCEPTABLE"},"time":1772032230825,"status":406}
2026/02/25 18:10:30 DEBUG : <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
2026/02/25 18:10:30 DEBUG : >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
2026/02/25 18:10:30 DEBUG : HTTP REQUEST (req 0xc0005a6b40)
2026/02/25 18:10:30 DEBUG : POST /api/m1/folder?access_token=cdafa903f9a271eb8c679d64ea5f704e512c1b9b3736383&limit=2147483647&offset=0 HTTP/1.1
Host: cloud.mail.ru
User-Agent: rclone/v1.73.1
Content-Length: 8
Accept: /
Content-Type: application/x-www-form-urlencoded
Accept-Encoding: gzip

home=%2F
2026/02/25 18:10:30 DEBUG : >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
2026/02/25 18:10:31 DEBUG : <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
2026/02/25 18:10:31 DEBUG : HTTP RESPONSE (req 0xc0005a6b40)
2026/02/25 18:10:31 DEBUG : HTTP/2.0 406 Not Acceptable
Content-Length: 100
Cache-Control: no-store, no-cache, must-revalidate
Content-Security-Policy: frame-ancestors 'self' https://myteam.mail.ru https://webim.internal.myteam.mail.ru https://app.workspace.vk.ru; report-uri https://cspreport.mail.ru/cloud?disposition=enforce&rev=cloud_26.10.23;
Content-Type: application/json; charset=utf-8
Date: Wed, 25 Feb 2026 15:10:31 GMT
Pragma: no-cache
Server: nginx
X-Email: support@glovertor.com
X-From: lightning_k8s
X-Host: cld-front-ext3.q
X-Page-Id:
X-Req-Id: 3a62c512ffab6e722f93773016cc59e1
X-Server: lightning
X-Timestamp: 1772032231
X-Timing: 0.0244691371917725
X-Ua-Compatible: IE=Edge
X-Upstream-Time: -

{"email":"support@glovertor.com","body":{"error":"NOT/ACCEPTABLE"},"time":1772032231036,"status":406}
2026/02/25 18:10:31 DEBUG : <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
2026/02/25 18:10:31 ERROR : error listing: file error 406 ()
2026/02/25 18:10:31 DEBUG : 3 go routines active
2026/02/25 18:10:31 NOTICE: Failed to lsd with 2 errors: last error was: file error 406 ()

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Start by reproducing rclone -vv --dump headers --dump bodies lsd mailru: against a Mail.ru for Domain account and inspect the /api/m1/file and /api/m1/folder requests shown in the report. Compare the 406 responses with the API behavior used by the official client or Total Commander; done means listing files and directories succeeds for this account.