In version 4.23 of Unreal Engine, you will most likely be presented with “/Engine/Generated/Material.ush(1964,56–152): error x3004: undeclared identifier ´TextureExternalSample_Decal`” if you try to sample a Media Texture in a Material configured for Deferred Decals with a Translucened Blend Mode.
To work around this issue, we’ve found, that configuring the Sampler Node to consider Mip Map Level Inputs and overriding the default Level with 0, the material compiles without any issues.
Originally published at https://biq.solutions on December 24, 2019.
