Toilet Problem

[y2kfroguy]

When my toilet flushes the tank fills up nearly full and does not drain. After a second flush it drains and the bowl fills normally. It always takes two times to flush. Any help would be great.

[DIY Guy]

You said the "tank" fills nearly full. Did you mean the "Bowl"?

If not, when the tank fills can you see if the flapper is open or not?