Made a new post, but it disappeared.

[Bionic]

How do I find out what happened to a new post I made but then disappeared?

When I go into my profile the post shows in "My Subscriptions". But when I click on the link to the post an error comes up that says....

An Unexpected Error has occurred.

• Your request failed. Please contact your system administrator and provide the date and time you received the error and this Exception ID: 3A1475A0.

  Click your browser's Back button to continue.

How do I contact a mod or admin here, to find out what's going on?

Thanks.