Today’s Question: I went to a folder from a trip of several years ago, looking for some videos I captured during that trip. I know these videos work fine, as I can access them from my operating system. But Lightroom shows a black exclamation point icon at the top right of each thumbnail, and when I put my mouse over that exclamation point it shows a message that says “Lightroom has encountered problems reading this video”. Is there anything I can do to get my videos back in Lightroom?
Tim’s Quick Answer: This scenario most likely indicates the cache for video files has become corrupted. To purge the cache so it can be rebuilt, click the “Purge Cache” button in the Video Cache Settings of the Performance tab in the Preferences dialog in Lightroom. When you restart Lightroom the videos should perform normally again.
More Detail: Lightroom uses a cache to help improve performance for playing videos within Lightroom. If that cache becomes corrupted for any reason, you may not be able to play some (or all) videos within your Lightroom catalog. The fact that these videos can be played normally outside of Lightroom further confirms that the issue is with Lightroom’s video cache.
Fortunately, it is very easy to purge the video cache, which will not cause any important data to be lost. When you then re-launch Lightroom you should be able to view all videos normally again, with the video cache being regenerated automatically.
As noted above, purging the cache for videos in Lightroom is very simple. First, bring up the Preferences dialog by going to the menu and choosing Edit > Preferences on Windows or Lightroom > Preferences on Macintosh.
Navigate to the Performance tab using the row of buttons across the top of the Preferences dialog, and look for the “Video Cache Settings” about midway down the dialog. At the far right of this dialog you can click the “Purge Cache” button to clear the video cache.
If you work with video on a regular basis in Lightroom, you can improve performance for video playback by increasing the cache size, provided you have adequate hard drive space available. The default value for Maximum Size for the cache is 3 GB, but you can increase the value. You can also turn off the “Limit video cache size” checkbox if you want to allow Lightroom to make use of as much free hard drive space as is available.
When you have adjusted the settings in the Preferences dialog, including purging the video cache, you can restart Lightroom to return to normal use of your videos.