Capture a short Jellyfin debug window and restore normal logging

The useful distinctions

• Debug logging is configured with logging.json rather than a frontend switch.
• Existing logging.json files should retain unrelated settings.
• A file present at the last server start can reload changes; a newly created file requires a restart.
• The documented normal default level is Information.

Define the capture first

Write a short sequence that reliably produces the issue before increasing log detail. Include the client action, expected result and approximate duration. This prevents a verbose capture from becoming a long record of unrelated browsing. A narrow window makes it easier to correlate the user action with server events and gives a maintainer a smaller, more useful starting point for investigation.

Change the minimum necessary

The example shows the documented level override as a small JSON fragment. On an installation that already has custom logging settings, merge that intention into the existing structure rather than replacing the whole file. Keep the original copy so restoration does not depend on memory. Whether a restart is required depends on when the override file came into existence, so note that detail in the capture record.

Close the experiment

As soon as the planned reproduction ends, return to the earlier logging configuration and record the end time. Preserve only the relevant files for investigation and review them before sharing because ordinary server logs can contain identifying paths or request details. A useful report explains what happened during the window and which log belongs to it. Large output alone does not establish that the underlying failure was captured.

A focused way to proceed

1. Preserve any existing logging.json and record the start of the reproduction window.
2. Set Serilog MinimumLevel Default to Debug while retaining other existing settings.
3. Restart only if the override file was created after the last server start.
4. Reproduce one issue, preserve the relevant log interval and restore the previous logging configuration.

Worked example · synthetic

{"Serilog":{"MinimumLevel":{"Default":"Debug"}}}

Read the comparison

DBG entries indicate increased detail, not by themselves the cause of the reported problem.

When to stop or ask for help

Provide a concise reproduction plus the matching reviewed log interval to official support.