bubbles on wall after painting it

[welshman22]

hi
i have just repainted my living room but 1 wall has got bubbles in it ??? the other 3 walls are fine i thought they would dry back but they look like blisters , can someone tell me what i have done wrong.
many thanks

 

[TheDec]

Does the problem wall happen to be an exterior wall ? And how long is it since you painted it.

Dec

 

[welshman22]

hi dec
thanks for getting back to me its been a few years i sand down before recoats and its only 1 wall the other 3 walls are fine, so is the living room off the dinning room both walls i done red and only the dinning room wall has blisted up i done the same prep for the both rooms there is no damp probs i used dulux matt paint .
many thanks steve

 

[JohnD]

Were there any traces of wallpaper paste or other glue on the wall? How did you clean and prepare it?

Was their any new filler?