When posting creatives into Yahoo! Japan, you may encounter such an error message:
Error: "YAHOO_JAPAN, INVALID_STRING_FORMAT adName:"
What Causes The Issue?
This problem is most likely caused by having the R Registration or ™ Trademark symbol in your creatives.
More details on the restriction for the special characters and symbols is listed here for your reference.
How To Fix The Issue
For Google, we would file an exemption request to get such ads approved. For Yahoo! Japan, however, please reach out to your Yahoo! Japan representative to ask if Yahoo! Japan sent the INVALID_STRING_FORMAT error to the platform because of the special characters and symbols.
If the above is not the case or you have more questions, please contact our Customer Support team, who will be happy to help investigate.