Please see WP staff post below in regarding the error.
I'm sorry to hear that this error is still happening. We're still currently looking into this matter. This issue is occurring sporadically to some players at certain times, however I will directly PM to those in here that have this issue. As for anyone else who is still having this particular issue, please PM me and Xanubis directly with the following details:
Exact time of issue
Date of occurrence
Browser Type (Firefox, Chrome, etc).
Device Type (mobile, desktop, etc.)
Again, I apologize for this technical issue. Thank you.
As for the issue, number of folks have mentioned using IE/Edge or Firefox resolved the error, so give that a try. If the error persists send the ticket to WP email instead. Click here for the instructions.