Altium "Unkown pin" error on every single component

Question

I know this problem has been discussed numerous times, however I cannot find the solution.

I am using Altium "Manufacturer part search" to download schematic symbols and footprints, which are then added to project via "Add existing to project...". In the window that pops up, I choose to add schematic and PCB library files, leaving the "altium integrated library" file unselected. From there I modify some of the schematic symbols (if needed), and leave others unmodified. Then I place the schematic symbol into my schematic document. In such manner I have designed all my schematic files.

The problem appears when I want to import changes into my newly created PCB document. Here I receive errors that say "Unkown pin: Pin .... ". Every single component, that was added by downloading schematics and footprints from "Manufacturer part search" has this error, doesn't matter if I modified it or not.

I have managed to fix one such error by replacing the schematic symbol and rewiring the connection (this had to be repeated multiple times to work) in schematic file. However, this does not work on other places.

I have tried restarting Altium, restarting the PC. Footprint designators match the schematic symbols. When in schematic, in parameter view, I can see the assigned footprint to the schematic symbol.

I have no idea what is happening. Please, help.

Adding messages window:

Answer 1

This happens when the designator of a pad in the footprint does not match the designator of the pin in the schematic symbol. This will often happen, for example, in a polarized capacitor where the footprint was created with pad designators"P" and "N", but the schematic symbol has the pins designated "1" and "2". This is just an example, but hopefully gives you an explanation of why it is not recognizing the pin. Check that the pin designators match the pad designators, otherwise Altium doesn't know which pin is supposed to link to which pad.

Answer 2

Thank you DerStrom8 for help. For anyone else having this problem - create your own schematic and pcb libraries, copy into them the contents downloaded from "manufacturer part search" and then assign footprints to schematic libraries.