When I open a
.gif
image in Photoshop – non animated – it always locks automatically and you cannot unlock it. Aside from that when try try to add text it will make a red block and convert the text to bitmap.You annoyingly have to copy and paste the document into a new document. Then layer from there.
Answer
It’s due to the Index Color mode. GIF and PNG8 use a locked color palette, therefore the layer gets locked to prevent unsupported changes. It’s also why the layer is titled Index.
To unlock it choose Image > Mode > RGB
from the menu.
Attribution
Source : Link , Question Author : TheBlackBenzKid , Answer Author : Scott