If I enter a long content on a page, it will fail to save

[qysaber]

If you enter the text of an entire book on a page, such as tens of thousands of words, an error will occur when saving

Failed to save entry: Form validation failed, please check your input

[pamtbaau]

See this issue: 1.7.32: Why impose max sizes for field types? Admin fails on large content sizes. #3643

As mentioned in one of the referred issues, it seems to be working when saving in "Expert" mode. Haven't tried it myself though...