This article is designed to show how to regenerate image and document previews in case they are corrupted or missing.
Resolution
To regenerate the previews:
- Navigate to Control Panel → Configuration → Server Administration.
- On the Resources tab, find to the Clean Up Actions at the bottom.
- Click Execute next to the Reset preview and thumbnail files for Documents and Media.
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Reset preview and thumbnail files for Documents and Media" option clears/deletes the previews and thumbnails of files. It will not regenerate the preview because it could create performance issues when regenerating previews all at once.
Therefore, as soon as the user visits the page where document exists in the document and Media (or click on any document), Liferay will initiate the Preview and thumbnails generation of those files.
For best results, be sure to use ImageMagick and Ghostscript; here are the ImageMagick Configuration instructions that will guide you through generating previews and thumbnails.