[Solved] No extrusion on first layer  

The two common causes for this are:

The bottom layer of the model is so fine/thin that the slicer is unable to extrude filament fine enough - this is common where models come to a point or a knife-edge at the base.

Or, due to a modelling error there is a detached part of the model, again micro-thin, beneath the intended base.

Sometimes it is enough to use the cut function at base level and discard the 'empty'  bottom section.

Cheerio,

RE: No extrusion on first layer

Or you think the model is flat on the bed but it's at a tiny angle. Using the F button to position it flat can fix that. Or—as @diem suggested—chop off a bit of the bottom with the cut function. 

For suggestions grounded in data, you may want to upload your project as a 3mf file. In Prusaslicer, go to File/Save project as, to create the 3mf file. Zip compress it (right click Compress on Mac and Win11, right click Send to/Compress on Win10) to turn it into a .zip file, which you can attach to a post on this forum. The forum software does not accept .3mf files, it has to be a .zip file.

The 3mf file contains not only the STL but also all your settings.

RE: No extrusion on first layer

Thanks to both of you.

I cut 0.5 mm off the bottom of the model and it solved the problem. 

It is a long and flat object. I guess it has an imperfection in model somewhere. Cutting it solved the issue. 

Thank for the tips and the insights!

RE:

I'm not famous yet, 😉 😇 , But If you can post a Zipped up .3mf project file exported from PrusaSlicer, I'll take a look and see if I can help. The .3mf file should be setup as you would when trying to print the part and will allow us to see all the settings as they pertain to the model in your project.

Note: if you do not Zip the file the forum server will not allow it to be posted.

Regards

Swiss_Cheese

P.s. Sorry I couldn't help it, Inside joke : )