Why do GIF images automatically lock the base layer in Adobe Photoshop?
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.
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.