I stand and waiting for Crafting and this Error comes..

Die Mod Belt Upgrader (2.0.2) hat einen Fehler verursacht, der nicht behoben werden kann.
Bitte informiere den Autor der Mod über diesen Fehler.

Error while running event BeltUpgrader::on_nth_tick(180)
BeltUpgrader/control.lua:189: attempt to index field 'items_to_place_this' (a nil value)
stack traceback:
BeltUpgrader/control.lua:189: in function 'upgrade'
BeltUpgrader/control.lua:77: in function <BeltUpgrader/control.lua:61>

Got the same error today :(.

After doing some digging it seems to caused by the mod https://mods.factorio.com/mod/Rocket-Silo-Construction. I'm not sure what exactly causes it, but changing row 188 in control.lua from:
if quality.level > candidate.quality.level then
to
if quality.level > candidate.quality.level and candidate.name ~= 'rsc-silo-stage2' then
the error no longer occurs. I assume it will also crash on the other stage and a proper fix is needed (or not).

Got the same error today :-(

I do not have that rocket silo mod

The mod Belt Upgrader (2.0.2) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event BeltUpgrader::on_nth_tick(180)
BeltUpgrader/control.lua:189: attempt to index field 'items_to_place_this' (a nil value)
stack traceback:
BeltUpgrader/control.lua:189: in function 'upgrade'
BeltUpgrader/control.lua:77: in function <BeltUpgrader/control.lua:61>

Start aper after i placed 'laser-wall' from laser walls.