Can you guys help me about this please?

The issue is related to how InDesign codes true type fonts. If you have the wherewithal to edit the epub, you could open up the content.opf files, search for x-font-ttf and replace it with: vnd.ms-opentype. It won't affect the functionality of the EPUB or the fonts in any way but it will get rid of those EPUB Checker errors. 

Hi @jeff_6736,

Could you please confirm the exact version of InDesign and the details of your operating system, as the experts asked earlier? That info will really help us narrow things down. Also, if you can, please share a short screen recording showing what steps you’re following and where exactly the error pops up. That would give me and the team a better idea of what’s going on and how best we can help.

Looking forward to your response.

Abhishek

There is an extensive discussion of this question here. Multiple ways to resolve this issue can be found in that discussion, the most relevant of which are:

• Maybe don't try to embed fonts?
• If you must, then use OTF 
• You can edit content.opf if you have to resolve this issue manually

What font typefaces are you using? Any special fonts? Any old fonts?

@jeff_6736

What platform, OS and InDesign versions? 

Jeff,

Maybe tell a bit about what you are doing?