Login Failure/Empty UI After Upgrade Due to Failed Database Version Check

1. Summary of Issue
   After upgrading Nginx Proxy Manager (NPM) from a stable version (e.g., 2.12.3) to any newer version (including :latest, which was 2.13.1 at the time of testing), the backend fails to recognize the existing database schema.

This prevents successful database migration and results in two immediate problems:

Login Fails with correct, existing credentials.

The application displays the new UI but an empty dashboard (no Proxy Hosts are visible).

2. Environment Details
   Operating System: Debian (Headless)

Container Management: Docker / Docker Compose / Dockge

Database: SQLite (Default, located in /data/database.sqlite)

Working Version (Before Breakage): jc21/nginx-proxy-manager:2.12.3

Failing Version(s) Tested: :latest (at time of testing, was likely 2.13.1)

3. Steps to Reproduce
   Start NPM container using version 2.12.3 with a pre-existing /data volume (containing proxy hosts and users).

Log in successfully and verify configurations.

Stop the container.

Update the docker-compose.yml image tag from 2.12.3 to :latest.

Run docker compose up -d (Triggers the upgrade and database check).

Access the UI and attempt to log in. (Login Fails).

4. Critical Log Snippet & Root Cause
   The container logs during the failed startup reveal that the migration process is skipped due to an unknown database version:

[11/5/2025] [8:30:15 AM] [Global ] › ℹ info Using Sqlite: /data/database.sqlite
[11/5/2025] [8:30:15 AM] [Migrate ] › ℹ info Current database version: none
This indicates the new application logic fails to read the version information from the existing SQLite file, treating the configured database as a new, uninitialized one and preventing necessary schema migration scripts from running.

5. Temporary Workaround
   The issue is fully resolvable by reverting the image tag back to jc21/nginx-proxy-manager:2.12.3 and restarting the container with the existing /data volume. This proves the data itself is fine, but the newer application code is incompatible with the version check.

Start by reproducing the upgrade from 2.12.3 with the existing /data volume and inspect the database version-check and migration startup path referenced by the logs. The fix is complete when the existing SQLite database is recognized, migrations run, login succeeds, and proxy hosts reappear after upgrading.