I imported a 9138x6310 TIF file and performed numerous adjustments including several masked adjustments.
The image exports fine at reduced resolution (2048x1414) but if I try to export at full resolution Lightroom gives the error: "An unknown error occurred. (1)". If I click "Turn off Masks" the image (without masks) exports at full resolution with no error. The exports are performed with the "Export..." command.
If instead I attempt to export with masks on via Publish Services ("jf Flickr: in this instance) the following error is reported: "Couldn't render image: AgNegative:renderToFile: <AgErrorID>dng_error_unknown</AgErrorID>".