It can be a result of a timeout during preview creation, caused by an extreme high amount of <rdf:li> tags within the images, which are created on previous image processing outside of censhare.

See https://forums.adobe.com/thread/2081839 for a detailed explanation and howto fix your images.

Howto check an image for <rdf:li> tags:

e.g. in Photoshop open the image, open menu "File/File information". Here switch to RAW-Data tab.

Now you see the xml structure looking like:

...
<photoshop:DocumentAncestors>
<rdf:Bag>
<rdf:li>##### COMMENT if you have huge amounts of this tag, it can cause a timeout ####</rdf:li>
...
</rdf:Bag>
</photoshop:DocumentAncestors>
<xmpRights:Marked>False</xmpRights:Marked>
<tiff:Orientation>1</tiff:Orientation>
<tiff:XResolution>3000000/10000</tiff:XResolution>
<tiff:YResolution>3000000/10000</tiff:YResolution>
<tiff:ResolutionUnit>2</tiff:ResolutionUnit>
<exif:ColorSpace>65535</exif:ColorSpace>
<exif:PixelXDimension>1020</exif:PixelXDimension>
<exif:PixelYDimension>1980</exif:PixelYDimension>
</rdf:Description>
</rdf:RDF>
</x:xmpmeta>

(end of file)
CODE


Newer clients simply jump over the <rdf:li> tags and thus prevent this problem.

This should no longer appear with systems starting from 04/2017.