Failed to load mods: Error while loading entity prototype "mining-drone" (unit): Missing filename in sound specification in property tree at ROOT.unit.mining-drone.walking_sound.variations
Modifications: Mining Drones 2 Remastered

There is another post just before yours that has a link to the sound fix, and the image fix.. Doing BOTH solved my unable to load errors.

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For those who want a manual fix for this
find line 16 in \Mining_Drones_Remastered\data\entities\attack_proxy\attack_proxy.lua
replace
filename = " base/graphics/icons/ship-wreck/small-ship-wreck.png",
with
filename = "core/graphics/empty.png",

Note: in your file you'll see 2 underscores - those are needed, just rename the base and core parts.

find line 327
replace
icon = "base/graphics/icons/ship-wreck/small-ship-wreck.png",
icon_size = 32,

with

icon = "core/graphics/empty.png",
icon_size = 1,

Same here for the underscores.

local sound = data.raw.tile["grass-1"].walking_sound
to
local sound = data.raw.tile["grass-1"].walking_sound.variations
in mining_drone_entity.lua fixes the problem.

""

Reset mod settings to default helped as well it seems.

FYI, that last section is in \Mining_Drones_Remastered\data\entities\mining_drone\mining_drone_entity.lua on line 7.

edit: I've made modifications to mods before, and gotten it to work... but somehow I can't get this one to. In the factorio-current.log file I'm getting "Opening file C:/Users/belin/AppData/Roaming/Factorio/mods/Mining_Drones_Remastered_2.1.4.zip/info.json failed -- error code -103 (Bad zip file)". I feel like I'm forgetting something on re-packaging an extracted mod so it can be read by Factorio.

edit 2: Never mind. I got it to work by using WinRAR to both extract it and re-package it. I had been using 7-zip for both, no idea why it was causing errors that WinRAR did not.