How do I fix 'an error occurred while loading a higher quality' for photos in the gallery?

Are you using iCloud Photos?

then you want to make sure, that you have plenty of free storage on your iPhone, so Photos has enough storage to download the high resolution originals to your iPhone, when you want to work with a photo. Also ensure that your iPhone is connected to Wi-Fi or allow Photos to use the cellular connection.

It's kinda tough to answer without knowing what sort of device you are talking about-- Do you have a Mac, an iPhone, an iPad, or what?

And could you give us more information?

• What models are your devices?
• What OS and/or iOS and/or iPadOS are you using? 
• Are you using iCloud Photos to synchronize your devices?
• Do you have “Optimize Storage” checked in Photos' settings?
• If this is a Mac, where does your Photos Library reside-- in the Pictures folder of your internal drive, or on an external drive? or on a network? on iCloud drive?
• Has this problem always existed, or did it just start? Can you think of anything that changed that might affect your device?

• How are these pictures different from others?
  • Did they all come from the same source?
  • Were they taken with your device, or
  • were they transferred to it?