Handle edge cases in encryption

**Problem**
When working with routes, the error messages could be more descriptive.

**Suggestion**
Improve error handling and add detailed error messages.

**Context**
This would help with debugging and maintenance.

No files, tests, or entry points are named. Start by locating route handling and encryption-related error paths, then identify the edge cases that currently produce vague messages; done means those cases return descriptive errors and are covered by relevant tests.

Written by the indexing model from the issue text.