Persistent Invalid session: Please try restarting Minecraft

Joining my server was working fine earlier in the night. Now i get the error message "Invalid session" with "please try restarting Minecraft" in red text underneath, immediately every time i try to log in, no time loading, immediate error message. I have attempted restarting Minecraft, restarting the launcher, restarting my computer, restarting the router, logging out and back in in the launcher, changing my password, launching without Optifine, updating Java, all to no avail.

Could I please get some help with this issue?