Pool liners on above ground and in ground pools are held in place by a track.
Above ground pool wall came out of track.
Check under the top rails and make sure the coping is still covering the liner and the rods are still covering the coping.
The liner can pop out of the track for various reasons including damage to the track liner shrinkage or water behind.
Wall anomalies are usually caused by the pool being out of.
You have a pool with the coping coming off and a wall out of the track.
We are in the process of putting up an 18ft above ground pool that we bought used.
Reapply boiling water as many times as needed to get the liner back into the track.
If the cove is intact and you did not need to drain your pool all is good.
When your repairs are made check the cove area on the inside of the pool.
We leveled the ground and have the pool tracking and wall in place.
The next two photos show damage that should be fixed.
For inground pools the track is usually part of the pool coping or connected to the pool wall so track replacement is very difficult.
Old pool liner coming out of coping track.
While you are cleaning the track out with a dull screwdriver or a popsicle stick inspect the track for any cracks or missing pieces.
We were very careful with everything and bought a new liner.
On one side i have noticed that the wall keeps popping out of the track and we push it back in and with in a few minutes it will be.
It is 2 years old and we took it down ourselves.
Clean out the track.
The liner only stays warm for a few seconds so you need to work quickly.
This is all important stuff if the liner is coming off the wall that should get fixed.
This type of repair can easily cause cove damage.
A wall out of the track usually happens when the track sinks and becomes too low.