Current State of BL2+TPS Modding, post-UHD DLC
Yesterday, on April 3, Gearbox released UHD Packs, or “Ultra High-Definition Texture Packs” for both Borderlands 2 and TPS. They’re available for free for all BL2+TPS users as a DLC download:
Along with those updates, though, the main EXE files for both games was updated, which broke BLCMM’s ability to apply hex-edits.
At the moment, a new version of BLCMM is still forthcoming, but there are some other ways to hex-edit your game, at least for BL2 (the Pre-Sequel is still in a somewhat weird state though).
Another is to use the new beta version of c0dycode’s “Hex Multitool”, which is available here. If you encounter problems with that release, please submit an Issue to c0dycode’s github Issue tracker. Note that TPS support for this is still a bit iffy, and might potentially not work at the moment.
You can expect that the next few days might remain a little chaotic for BL2+TPS modding, of course, but with either of those methods, you should be able to get your BL2+TPS mods working again for the time being.