Blueprint mayhem

[Durahl]

While Building stuff using Blueprints and UP/DOWNgrading it I came across this little gem:

The Blueprint in question has Tier II Assemblers in it but since I was running low on Tier I Belts I decided to upgrade them ( and the Tier II Inserters ) to their next Tier when, after taking my eyes off for a moment, I came across a bunch of Tier III Assemblers despite not even having the research done for them as can be seen from both my Crafting Window and the Research one:

I knew one can cheese Circuit Network Cables from a Blueprint despite not having the necessary research but this is new to me xD

[Qon]

This is the probably the most broken and exploitable bug in Factorio history that I've heard about. If we can discover how this can be used reliably for other upgradable things then it can save a lot of time on speedruns. It will probably introduce the "glitchless any%" category to Factorio (since glitchless is no longer the same category as any%).

[DaveMcW]

Can you provide detailed steps to reproduce this?

I was able to upgrade a blueprint without the tech, but my robots refuse to build it.

[Loewchen]

What version of the game is this?
Post a save and exact steps to produce the issue please.

[Rseding91]

Yes; we require a way to reproduce this.

[Qon]

^ So many aspiring speedrunners salivating at the thought of snatching the WR with a new trick

[Durahl]

Like I said, I didn't even see how it happend but if I had to make a guess then it would have something to do with the drone already carrying an Assembler when I issued an Upgrade Plan for the entire area to deal with lack of Tier I Belts which also issued an upgrade for the yet to be placed but already inbound Tier II Assembler.

[Rseding91]

Like I said, I didn't even see how it happend but if I had to make a guess then it would have something to do with the drone already carrying an Assembler when I issued an Upgrade Plan for the entire area to deal with lack of Tier I Belts which also issued an upgrade for the yet to be placed but already inbound Tier II Assembler.

We specifically have a test and code to prevent that from happening so I doubt that's it.