Thumbnail Issue - Video Preview Thumbnails Stuck at 0.0% After Restart

[UsamaWaheed 8]

Description:
I’m migrating from Plex to Emby and currently setting up and testing my libraries. I’ve run into an issue where video preview thumbnails remain stuck at 0.0% after a reboot.

Steps taken / timeline:

• Created libraries: Anime, Movies, TV Series.

• Initial scans completed successfully.

• Adjusted /mnt mapping for media paths and rescanned → all media added.

• Enabled video thumbnail generation for all three libraries.

• Thumbnails began generating (progress reached ~45%).

• Stopped the thumbnail extraction task and rebooted.

• After reboot, the task stays at 0.0% permanently.

• Logs showed errors related to the Iconic plugin → removed plugin.

• Re-ran thumbnail generation task → still stuck at 0.0%.

• Disabled video thumbnails on all libraries → re-enabled for one → ran Refresh Metadata with delete & regenerate thumbnails option.

• Now I see ffmpeg activity in the logs creating thumbnails, but:

  Extraction shows no progress (always 0.0%).

  Library scan sits at 90% indefinitely.

  Unsure how long the task should take or if it’s working correctly.

What I’m worried about:
Even though ffmpeg appears to be generating thumbnails in the logs, the UI never reflects progress, and the library scan does not complete. I’m unsure if the process will ever finish or if something is broken.

Attachments:

• Full logs since server setup (last few days).

Environment:

• Emby Server 4.9.1.80 (Docker, running on Unraid 6.12.24)

• Libraries stored under /mnt/

 

Attaching logs as 7z & zip file. They have the same data - chose whichever version you prefer. Compressed them as the total size is greater than 195mb

embyserver-63896199503.7z embyserver.zip

[Luke 42077]

HI, the extraction progress in the scheduled task is based on the total number of videos. The progress won't move during the extraction of any one single video. Does that help with your issue?

[UsamaWaheed 8]

I let the process run for several hours and noticed it completed 100/960 movies during that time, but the progress indicator stayed stuck at 0.0% until it suddenly finished. This makes it hard to tell if the job is actually progressing without constantly checking the logs.

As a suggestion, it would be really helpful if the UI could show some indication of activity — even something simple like “processing media X, Y, Z…” — so we know it’s working. I understand percentages can be tricky to implement accurately, but Plex, for example, shows on the dashboard which file it’s generating thumbnails for, which makes it much easier to gauge that it is indeed working and not stuck on something.

 

Plex example:

 

 

[Luke 42077]

Hi, yes that's something I've been meaning to add. Thanks.

[UsamaWaheed 8]

51 minutes ago, Luke said:

Hi, yes that's something I've been meaning to add. Thanks.67

That would be fantastic — hopefully it’s a relatively easy enhancement and can make its way into the next release.

Since the thumbnails are now being created successfully, I’ll mark this ticket as closed. That said, I may need to open a follow-up if the Iconic plugin continues to crash once all thumbnails have been generated.

[Luke 42077]

Yea I don't have an ETA but it's definitely on our radar. Thanks.