Error when signing with Twig date filter in signature field

[thomas-zic]

Describe the bug

When adding the following Twig code into the signature field, the preview renders correctly, but an error occurs during the signing process: {{ ServerSignatureDate|date("d/m/Y H:i:s T", "Europe/Paris") }} ; Interestingly, using the same Twig expression in the footer works without any issues. Removing this Twig snippet from the signature field resolves the problem completely.

To reproduce

1. Add the following Twig expression into the signature configuration: {{ ServerSignatureDate|date("d/m/Y H:i:s T", "Europe/Paris") }}
2. Observe the signature preview — it renders correctly.
3. Proceed to sign the document.
4. An error occurs during the signing process.

Expected behavior

No response

Screenshots

Environment information

Nextcloud version: 32
LibreSign version: 12.4.4
Deployment: Docker

Additional context

No response