macOS Tahoe 26.1 breaks VeraCrypt password input containing the character “ä”

[Paxton Polar]

Environment:
* Hardware: Mac mini M4 Pro (2024)
* OS: macOS Tahoe 26.1 (problem started immediately after this update)
* VeraCrypt version: 1.26.24 (FUSE-T build)

Summary:
After updating to macOS Tahoe 26.1, VeraCrypt can no longer open volumes whose passwords contain the Scandinavian character “ä”. VeraCrypt rejects the password and shows the usual list of mismatch hints. Immediately before the update the same volumes opened normally.

Details:
* Passwords without Scandinavian characters still work correctly.
* Any password containing “ä” is rejected.
* When VeraCrypt displays the entered password in the incorrect-password dialog, the “ä” character is missing entirely, even though it was typed.
* This strongly suggests that macOS 26.1 no longer passes the character correctly to VeraCrypt’s password input layer (possibly an input method / UTF-8 handling regression).
* Restoring the affected container from backup (known-good state) does not help — the volume still cannot be opened on macOS 26.1.
* The issue did not occur on macOS Tahoe 26 / earlier versions; it started immediately after updating to Tahoe 26.1.

Steps to reproduce:
1. On macOS Tahoe 26.1, launch VeraCrypt.
2. Attempt to mount a volume whose password contains “ä”.
3. VeraCrypt rejects the password and removes the “ä” from the password dialog field. All the other letters within the password remain intact.

Expected behavior:
VeraCrypt should receive and process the UTF-8 “ä” character exactly as typed, as in all previous macOS versions.

Actual behavior:
The “ä” character appears to be stripped or transformed before VeraCrypt receives it, making valid passwords invalid.

Notes:
This may be a regression in macOS Tahoe 26.1 input handling or keyboard event processing affecting non-ASCII characters. Other applications on the same system accept “ä” normally, which suggests the issue affects password fields or raw input APIs used by VeraCrypt.

[Paxton Polar]

I tested the exact same VeraCrypt volume on another machine:
* MacBook Air M1 (2020)
* macOS Sequoia 15.6.1
* VeraCrypt 1.25.9

On this system the volume opens normally using the password that contains the “ä” character.

This confirms several things:
* The volume itself is intact and not corrupted.
* The password is correct and unchanged.
* The issue is not reproducible on macOS Sequoia 15.6.1, only on macOS Tahoe 26.1.
* This strongly suggests the regression occurs specifically in macOS 26.1’s keyboard/input handling or related APIs used by VeraCrypt to collect password input.
* The missing “ä” character (disappearing from the password echo in the failure dialog) is therefore a symptom of macOS not passing the character to VeraCrypt at all—or passing it in altered form.

Because the password works on Sequoia but fails on Tahoe, the evidence points to an OS-level bug that affects non-ASCII characters in password fields (possibly only in applications using low-level or secure input APIs like VeraCrypt).

I have now migrated the data to a new volume with an ASCII-only password to work around the issue. Still, I wanted to provide this follow-up so the root cause can be investigated.