Command Blocks error

Could you please provide the commands you tried to execute?
Also, don't put FallingSand in between quotes.

All 1.8 versions (no 1.9)

16350382

/summon FallingSand ~1 ~30 ~13 {Block:stained_hardened_clay,Data:14,Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:/summon FallingSand ~1 ~15 ~-9 {Block:redstone_block,Data:0,Time:1,DropItem:0}},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:tellraw @p ["",{"text":"\n\n\n\n'Halloween Decorations' in Minecraft [1.8.x] ","color":"gold","bold":true},{"text":"by ","color":"none","bold":false},{"text":"TheRedEngineer","color":"red","bold":true},{"text":"\n youtube.com/c/TheRedEng\n\n","color":"gold","clickEvent":{"action":"open_url","value":"http://www.theredengineer.com/"},"hoverEvent":{"action":"show_text","value":{"text":"","extra":[{"text":"click to open link ⤴","color":"dark_blue"}]}},"bold":false},{"text":"Credit TheRedEngineer if you are using this creation\nDon't re-upload this command: provide my website link!!\n\n\n","color":"red"}]},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:/summon FallingSand ~ ~-2 ~-5 {Block:command_block,Data:0,TileEntityData:{Command:execute @e[type=Blaze,name=Pumpkin_Balloons] ~.4 ~.6 ~.4 /summon ArmorStand ~ ~ ~ {CustomName:"ASPKBL",Invisible:1,Invulnerable:1,NoGravity:1,PersistenceRequired:1,Equipment:[{id:blaze_rod,Count:1},{},{},{},{}],DisabledSlots:2039583,Pose:{RightArm:[-100f,0f,0f]}}},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @e[type=Blaze,name=Pumpkin_Balloons] ~.4 ~.4 ~.4 /summon ArmorStand ~ ~ ~ {CustomName:"ASPKBL",Invisible:1,Invulnerable:1,NoGravity:1,PersistenceRequired:1,Equipment:[{id:blaze_rod,Count:1},{},{},{},{}],DisabledSlots:2039583,Pose:{RightArm:[-100f,0f,0f]}}},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @e[type=Blaze,name=Pumpkin_Balloons] ~.4 ~1.4 ~.4 /summon ArmorStand ~ ~ ~ {CustomName:"ASPKBL1",Invisible:1,Invulnerable:1,NoGravity:1,PersistenceRequired:1,Equipment:[{id:blaze_rod,Count:1},{},{},{},{}],DisabledSlots:2039583,Pose:{RightArm:[-100f,0f,0f]}}},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @e[type=Blaze,name=Pumpkin_Balloons] ~-2 ~ ~1.5 summon Giant ~ ~ ~ {CustomName:"HMCG1",Equipment:[{id:pumpkin,Count:1},{},{},{},{}],DropChances:[0.0F,0.085F,0.085F,0.085F,0.0F],Invulnerable:1,Rotation:[210f,0f],PersistenceRequired:1,NoAI:1,Silent:1,ActiveEffects:[{Id:14,Amplifier:0,Duration:199999980,ShowParticles:0b}]}},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @e[type=Blaze,name=Pumpkin_Balloons] ~1.5 ~-2 ~2 summon Giant ~ ~ ~ {CustomName:"HMCG1",Equipment:[{id:pumpkin,Count:1},{},{},{},{}],DropChances:[0.0F,0.085F,0.085F,0.085F,0.0F],Invulnerable:1,Rotation:[120f,0f],PersistenceRequired:1,NoAI:1,Silent:1,ActiveEffects:[{Id:14,Amplifier:0,Duration:199999980,ShowParticles:0b}]}},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @e[type=Blaze,name=Pumpkin_Balloons] ~1 ~ ~-3 summon Giant ~ ~ ~ {CustomName:"HMCG1",Equipment:[{id:pumpkin,Count:1},{},{},{},{}],DropChances:[0.0F,0.085F,0.085F,0.085F,0.0F],Invulnerable:1,Rotation:[0f,0f],PersistenceRequired:1,NoAI:1,Silent:1,ActiveEffects:[{Id:14,Amplifier:0,Duration:199999980,ShowParticles:0b}]}},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @e[type=Item,score_hmcItm_min=7,score_hmcItm=7] ~ ~ ~ execute @e[type=Item,score_hmcItm_min=6,score_hmcItm=6,r=1] ~ ~ ~ kill @e[type=Item,score_hmcItm_min=6,score_hmcItm=7,r=2]},Time:1,DropItem:0}}}}}}}},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:/summon FallingSand ~2 ~-1 ~-5 {Block:command_block,Data:0,TileEntityData:{Command:execute @a ~ ~ ~ scoreboard players reset @e[name=ASHLGR,rm=4]},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @a ~ ~ ~ scoreboard players add @e[name=ASHLGR,r=3] hmcTmr 1},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:tp @e[type=Silverfish,name=Grave] ~ ~-400 ~},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @e[type=Silverfish,name=Grave] ~ ~-1.1 ~1 summon ArmorStand ~ ~ ~ {CustomName:"ASHLGR",Marker:1b,Invisible:1,Invulnerable:1,NoGravity:1,PersistenceRequired:1,Equipment:[{},{},{},{},{id:stone_slab,Count:1}],DisabledSlots:2039583,Pose:{Head:[90f,0f,0f]}}},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @e[type=Silverfish,name=Grave] ~ ~ ~ fill ~ ~-1 ~1 ~ ~-1 ~ dirt 1},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @e[type=Item,score_hmcItm_min=11,score_hmcItm=11] ~ ~ ~ execute @e[type=Item,score_hmcItm_min=12,score_hmcItm=12,r=1] ~ ~ ~ kill @e[type=Item,score_hmcItm_min=11,score_hmcItm=12,r=2]},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @e[type=Item,score_hmcItm_min=11,score_hmcItm=11] ~ ~ ~ execute @e[type=Item,score_hmcItm_min=12,score_hmcItm=12,r=1] ~ ~ ~ summon Item ~ ~ ~ {CustomName:"Grave",CustomNameVisible:1,Item:{id:spawn_egg,Damage:60,Count:1,tag:{HideFlags:1,display:{Name:"Grave"},ench:[{id:35,lvl:0}]}}}},Time:1,DropItem:0}}}}}}}},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:/summon FallingSand ~2 ~ ~-6 {Block:command_block,Data:0,TileEntityData:{Command:execute @e[type=Item,score_hmcItm_min=11,score_hmcItm=11] ~ ~ ~ execute @e[type=Item,score_hmcItm_min=12,score_hmcItm=12,r=1] ~ ~ ~ playsound mob.skeleton.say @a ~ ~ ~ 10 1},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @e[type=Item,score_hmcItm_min=11,score_hmcItm=11] ~ ~ ~ execute @e[type=Item,score_hmcItm_min=12,score_hmcItm=12,r=1] ~ ~ ~ particle witchMagic ~ ~ ~ .1 .1 .1 1 100 force},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:scoreboard players set @e[type=Item] hmcItm 12 {OnGround:1b,Item:{id:"minecraft:stone_slab"}}},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:scoreboard players set @e[type=Item] hmcItm 11 {OnGround:1b,Item:{id:"minecraft:dirt",Count:2b}}},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @e[name=ASHLSK2] ~ ~ ~ detect ~ ~1 ~1 air 0 kill @e[name=ASHLSK2,r=0]},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @e[name=ASHLSK2] ~ ~ ~ detect ~ ~1 ~1 air 0 summon Item ~ ~ ~1 {CustomName:"Human skeleton",CustomNameVisible:1,Item:{id:spawn_egg,Damage:51,Count:1,tag:{HideFlags:1,display:{Name:"Human_Skeleton"},ench:[{id:35,lvl:0}]}}}},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @e[name=ASHLSK2] ~ ~ ~ detect ~ ~1 ~1 air 0 kill @e[name=ASHLSK1,c=6]},Time:1,DropItem:0}}}}}}}},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:/summon FallingSand ~ ~1 ~-6 {Block:command_block,Data:0,TileEntityData:{Command:execute @e[type=Item,score_hmcItm_min=7,score_hmcItm=7] ~ ~ ~ execute @e[type=Item,score_hmcItm_min=6,score_hmcItm=6,r=1] ~ ~ ~ summon Item ~ ~ ~ {CustomName:"Pumpkin balloons",CustomNameVisible:1,Item:{id:spawn_egg,Damage:61,Count:1,tag:{HideFlags:1,display:{Name:"Pumpkin_Balloons"},ench:[{id:35,lvl:0}]}}}},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @e[type=Item,score_hmcItm_min=7,score_hmcItm=7] ~ ~ ~ execute @e[type=Item,score_hmcItm_min=6,score_hmcItm=6,r=1] ~ ~ ~ playsound mob.skeleton.say @a ~ ~ ~ 10 1},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @e[type=Item,score_hmcItm_min=7,score_hmcItm=7] ~ ~ ~ execute @e[type=Item,score_hmcItm_min=6,score_hmcItm=6,r=1] ~ ~ ~ particle witchMagic ~ ~ ~ .1 .1 .1 1 100 force},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:scoreboard players set @e[type=Item] hmcItm 6 {OnGround:1b,Item:{id:"minecraft:pumpkin",Count:3b}}},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:tp @e[type=Ghast,name=Magic_Plant] ~ ~-400 ~},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @a[ry=-45,rym=-134] ~ ~ ~ execute @e[type=Ghast,name=Magic_Plant] ~ ~ ~ /summon Ghast ~ ~-4.6 ~ {CustomName:"Grumm",ExplosionPower:0,Invulnerable:1,PersistenceRequired:1,NoAI:1,Silent:1,Rotation:[90f,0f]}},Time:1,DropItem:0,Riding:{id:"FallingSand",Block:command_block,Data:0,TileEntityData:{Command:execute @a[ry=-135,rym=135] ~ ~ ~ execute @e[type=Ghast,name=Magic_Plant] ~ ~ ~ /summon Ghast ~ ~-4.6 ~ {CustomName:"Grumm",ExplosionPower:0,Invulnerable:1,PersistenceRequired:1,NoAI:1,Silent:1}},Time:1,DropItem:0}}}}}}}},Time:1,DropItem:0}}}}}}}

This is an invalid command in 1.12.2 and above. NBT syntax has changed a little bit.