I have tried easily over 50 times to get past the last step (confirm), and no luck. Same error 500.300588. In the meantime, even given the many complaints to this site, not one comment by HHS as to what this error represents in real terms so we as users can try to make a correction. Phone support can't get by this error either, as I've walked through the application twice with them...They get the same error on their end, and they can't proceed. I've never had such a bad experience over something this important.
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