Under certain circumstances, a file may not show a preview, but only a placeholder. This may be caused by a preview calculation error.
The following tips will help you solve this problem💪
Basic information
The preview calculation of files is performed by the Derivateservice.
This service uses integrated third-party tools that calculate previews and downloads for most file formats (e.g. ImageMagick for image formats or Ghostscript for PDF).
Sometimes the calculation may encounter technical obstacles. However, this can be influenced by by adapting to the required needs and the available hardware.
Note that no preview can be calculated in the following cases:
When InDesign files are involved. To calculate previews for InDesign files, you will need our InDesign Plugin.
If the file format is not supported by our integrated third-party tools.
Additional Information
Documentation: Supported file types (most common file types)
Documentation: InDesign Plugin
Troubleshooting
Refresh previews
As an administrator, you can refresh the preview for a file:
Go to the Files module and select the file(s) with the missing preview.
Click the button
in the toolbox to restart the calculation.Depending on the file size and the number of selected files, the calculation may take some time.
Reload the page and check that the preview has been calculated.
If the preview is still not displayed, proceed to the next steps.
Please note
The "Refresh previews" button starts the processors for calculating preview derivatives and for extracting metadata from files. This has the following effects:
Individually tagged metadata is preserved.
The processor for folder-based tagging is not restarted.
Workflows may be triggered, which can affect processing time.
Check log entries
A failed calculation usually leaves an error in the log. Check the log entries:
In the system: Go to admin snap-in Protocol overview > Application logs
In the system: Go to admin snap-in Protocol overview > Request management
(in the filter panel, select object type "File process")In Docker: Enter the following command:
docker compose logs -f 4allportal.
Make sure you are in thedocker-compose.yamldirectory.
Check the log entries for error messages from the following third-party tools:
convertidentifyexiftool
If one of these tools reports an error, it either has problems with a specific file (e.g., "resource exhausted") or has reached technical limits in its calculations.
In this case, adjusting the configuration may help.
Adjust limits
The preview calculation can be influenced and optimized by adjusting the limits for the third-party tools used. These limits are set directly in the file docker-compose.yaml.
The limits for ImageMagick, the tool used to calculate image files, can be adjusted with the following parameters:
| Maximum disk usage |
| Maximum use of memory |
| Maximum file height |
| Maximum file width |
| Maximum number of pixels |
Please consider the available hardware when customizing, as the software is scalable only within the limits of the hardware performance.
Additional Information
Technical documentation: Derivateservice (tools and available parameters)
Technical documentation: Docker image (default and configuration)
These tips should help you successfully calculate a missing preview.
Feel free to contact us if you are missing any information👍