Part of the CustodyStress archive of observed Bitcoin custody incidents
CS-01142
Investigation by the community revealed that a firmware change had altered how
IndeterminateCase description
A Trezor user reported on the Trezor forum in early 2023 that a passphrase they had used reliably for 18 months had stopped working after a firmware update. Investigation by the community revealed that a firmware change had altered how the device handled certain Unicode characters in passphrases—specifically, characters outside the ASCII range. Passphrases that included accented characters, emoji, or non-Latin Unicode behaved differently after the update, producing a different derived wallet. The change affected a small cohort of users whose passphrases included such characters.
Custody context
| Stress condition | Passphrase unavailable |
| Custody system | Hardware wallet (single key) |
| Outcome | Indeterminate |
| Documentation | Unknown |
| Year observed | 2023 |
| Country | International |
Structural dependencies observed
What this illustrates
The seed phrase was there, but the passphrase that unlocked it was gone. Both are required. It's not clear whether anyone ever regained access.
Outcome interpretation
Not enough information is available to determine the outcome.
Source
Privately Reported
Evidence type
Forum post
Related cases involving passphrase unavailable
217 cases involve passphrase unavailable
274 cases involve hardware wallet (single key)
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This archive documents observed custody survivability failures. It does not attempt to document all Bitcoin losses or security incidents.
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Framework references
Where Bitcoin Custody Intersects Legal and Fiduciary Authority
Where custody creates gaps in estate planning, fiduciary duty, and professional responsibility.
Professional Scope Boundary Matrix
What each professional or product covers, what they do not, and where gaps form between them.
The Independent Assessment Layer in Bitcoin Custody
How independent diagnostic layers emerge when multiple parties depend on shared infrastructure.
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