Ronald from the Google Merchant Center team posted on a new error some merchants might see. The post is at the Google Merchant Center Help forum.
The new error is named "offer too big" and can occur when your feed has an "unusually high number of characters" that are not relevant to the product in the feed. Ronald explained:
In the last few days, some of you may have noticed a new error message in your data feed details page called "offer too big." This error message is for items which have unusually high number of characters and may contain javascript code, HTML, etc instead of relevant text. To resolve this issue, please remove the unnecessary text from your items and include only relevant information in the values of the attributes.
So if you get this error, you can fix it by dropping out any excess HTML or code from your feeds.
Forum discussion at Google Merchant Center Help.