Sign in failure (wrong password attempt) on ProtonDrive for passwords with special characters

I have configured rclone according to "rclone config" for proton-drive using a password in the style of: ÂMÂdÈT¤¤ç]?×Ð#è9ñdã*Û+PM#.(©Ýº:?/¬+àì±ÕA'#¿ .

When trying to test the connection it fails:

OOO@UUU:/srv# rclone lsd proton:
2025/11/23 15:33:41.294117 WARN RESTY 401 GET https://mail.proton.me/api/core/v4/users: Invalid access token (Code=401, Status=401), Attempt 1
2025/11/23 15:33:41.294420 ERROR RESTY 401 GET https://mail.proton.me/api/core/v4/users: Invalid access token (Code=401, Status=401)
2025/11/23 15:33:41.388511 WARN RESTY 422 POST https://mail.proton.me/api/auth/v4/refresh: Invalid refresh token (Code=10013, Status=422), Attempt 1
2025/11/23 15:33:41.388576 ERROR RESTY 422 POST https://mail.proton.me/api/auth/v4/refresh: Invalid refresh token (Code=10013, Status=422)
2025/11/23 15:33:48.995680 WARN RESTY 422 POST https://mail.proton.me/api/auth/v4: Incorrect login credentials. Please try again. (Code=8002, Status=422), Attempt 1
2025/11/23 15:33:48.995738 ERROR RESTY 422 POST https://mail.proton.me/api/auth/v4: Incorrect login credentials. Please try again. (Code=8002, Status=422)
2025/11/23 15:33:48 Failed to create file system for "proton:": couldn't initialize a new proton drive instance: 422 POST https://mail.proton.me/api/auth/v4: Incorrect login credentials. Please try again. (Code=8002, Status=422)

I tried on different machines with different versions - with the same result. On Proton I get the error:

Sign in failure (wrong password) (attempt)
Nov 23, 2025, 3:33 PM
rclone
macos-drive
1.0.0-alpha.1+rclone

The password was definetly copied right, 2FA as well.

I changed my password got rid of special characters like " ' ` - same result. So I got rid of all special characters, except ? # $ (I think) - which worked.

[XXX@YYY:~]$ rclone --version
rclone v1.71.2
- os/version: nixos 25.11 (64 bit)
- os/kernel: 6.17.5 (x86_64)
- os/type: linux
- os/arch: amd64
- go/version: go1.25.2
- go/linking: dynamic
- go/tags: cmount

AAA@BBB:/srv# rclone --version
rclone v1.65.2
- os/version: turrisos 7.2.3
- os/kernel: 5.15.148 (armv7l)
- os/type: linux
- os/arch: arm (ARMv7 compatible)
- go/version: go1.19.13
- go/linking: dynamic
- go/tags: none

On mail-clients or through web-login my more sophisticated passwords are fine, and I don't consider it as a beautiful solution to use something less secure for rclone - maybe I did something wrong - but to me it seemed like a bug.

Thanks and have a great day.

Start by reproducing the failure with rclone config and rclone lsd proton: using a password containing the reported special characters. Review the Proton Drive authentication requests shown in the log, especially /api/auth/v4 and /api/auth/v4/refresh, and compare them with a password that succeeds. Done means authentication works without weakening the password and the relevant behavior is covered by a reproducible check.