If you have more than one million tokens to replace, you will need to increase the value in the Undo Max Number text box in the General tab of configuration properties. I might increase this default value, and also add the warning message box when undo may not be available.

I don’t think it’s the problem. In fact my file only have 931380 lines, and only 894261 entries were replaced. The max undo number should be 1,000,000(However this value seems can not be set more larger).

Thanks for your reply. Please let me know if you need more information for recreate this issue.