DVD player will not play Dvds error message saying incorrect disc

I don't understand your problem.
Is it the TV or is it the DVD? You say you tried other dvds and the problem is still there. Looks like the TV is the problem. Sometimes it's hard to help people when they only mention on screen issues. How can first DVD say 'incorrect disk' and then another dvd, and another still say 'incorrect disk'? It just doesn't seem to make sense. Is the contents on the disk a computer recorded movie, film or home movie? If so, you have to record the film on the disk with a format that accept the DVD. Could the DVD be a Blu-Ray, can it play a number of video formats, DVD, DivX, KviD DVD, etc.? Try first with a purchased movie DVD disc, if it doesn't work, then the DVD is faulty. DVD players these days are meant to play a wide range of video format, including CD discs. If you have an old DVD player, you may not play latest discs. But if the DVD is incorporated with the TV, then you have to insert a new movie and see if it plays. Go to an appliance or TV DVD store and talk to them. Or you can purchase a new movie and insert it in. If it doesn't work, you can always return it. As you said, you've tried different DVDs, sounds like it is a separate DVD player. If so, try other movie discs. I get the same warning only when I insert discs with movies I recorded on my computer, such as Pinnacle video editor.

Try a lens cleaning disk! Could be dust or dirt on the lens!

This shows up in older DVD player that do not play recorded DVDs.

DVDs are coded for different areas of the world. If you bought the DVD from an online source it may not play on your format of DVD player.

All discs will not play with this set. It is not a fault. It is a common trouble to this model.

LG DVD Player Disc Tray opens & closes automatically & unnecesarrily

Are you loading to play or to record?
Commercial DVDs should play.
DVDs for recording may not be recognized by your drive. First make sure that the disc is blank. You must insert a blank disc of the proper format: DVD-R or RW, DVD+R or RW. Even with the proper format, some brands may not behave the same way as other brands.

Is it the Panasonic Portable DVD player

you may have a different region on you dvd to your dvd player. say your dvd player was 1st region you can only play 1st region dvds if you try a 2nd or 3rd region dvd it would not work. you can go to a dvd specialist to get it tuned to a multiregion dvd player.
go to a dvd player shop and ask if they know how to tune it.

I had the same problem with my recorder except that it wouldnt play any discs at all.. I finally unplugged the recorder and left it unplugged for 16 hours. Now it is fine. I am not getting any error messages.