No symbol found in library

Hello,

I try to develop a new PCB starting with a project already made and published.
When open xx.sch a dialog box says

This schematic currently uses the project symbol library list look up method for loading library symbols

Then, when mapping, it complains: (just a few lines as example)

Warning: No symbol “LM317_SOT223” found in symbol library table.
Warning: No symbol “Diode_Bridge” found in symbol library table.
Warning: No symbol “CONN_01X02” found in symbol library table.
Warning: No symbol “CP1” found in symbol library table.
Warning: No symbol “C” found in symbol library table.
Warning: No symbol “POT” found in symbol library table.
Warning: No symbol “C” found in symbol library table.
Warning: No symbol “LM317_SOT223” found in symbol library table.
Warning: No symbol “POT” found in symbol library table.
Warning: No symbol “R” found in symbol library table.
Warning: No symbol “D” found in symbol library table.
Warning: No symbol “C” found in symbol library table.

Using KiCad 5.1.10on Win10

My old own projects load perfectly

What library setting am I missing ?

Thanks a lot,
Have a nice day,

R, D and C are very basic symbols in Device

Back in V4 days most libraries had slightly different names, usually plural. I wonder if your old project was V4?

Hello David,

When I open sch file and see the circuit diagram all components appear with two question marks. As undefined. On the bottom right says
KiCad EDA eeschema (5.1.10)

I have the original pro, sch files. Do you want I look for some info inside those text files ?

Thanks so much !
Horacio

When I do a search for “Diode_Bridge” in the Footprint editor (KiCad V5.1.10) then it shows a bunch of them, but all have longer names, so no exact matches.

This seems to confirm that your library tables for that old project are likely from KiCad V4.

KiCad has a **[ProjectName]-Cache.lib" file for each project, which has a backup of all schematic symbols. You can make this into a project specific library with some effort.

But you’re having troubles with PCB footprints.
Already in KiCad V4, all used footprints were saved / cached in the PCB file.
You can right click them, then "Edit with Footprint Editor [Ctrl + e]**, and then in the Footprint Editor, create a new library and add your footprints into that (project specific) library.
If you do so, you also have to update the schematic to use the footprints of your newly created library. It is a bit of work and a nuisance, but it one of the ways to make your project more robust and future proof.

The FAQ on this website has a lot of tutorials about various topics and is the most upto date documentation at this moment.
For example:

The double question mark symbols on the schematic: [??] appear when there is a problem with the schematic symbol libraries.

First:
Do you know in which version of KiCad the project was first made?

The **[ProjectName]-Cache.lib" file is quite an important file and it should have a backup of all used schematic symbols, You should not delete this file, and always back it up with your project. Do you still have (a valid version) of this file for your project?

For more info, read this FAQ article:

Hello Paul, thanks for your time !

I have carefully read your answers.
I only have pro, sch ad gbr files.

I don’t have the cache-lib file.

Perhaps reinstalling V4 ?
Is it possible ? Or V4 will override my actual V5 ?

Anyway, I think it will be quicker to restart from scratch in V5. Is a very simple voltage and current regulator with two linear ICs.

Thanks again, have a nice day !
Horacio

I used to panic whenever I saw those [??] symbols.
Without he cache file it’s difficult to repair.

One way to repair it is to change the library references.
KiCad still has most of the info in your schematic, it is (mostly) just the graphics of the symbol that is missing.
To repair this, select any of the [??] symbols and then edit it’s properties, and then use the browse function to find a suitable replacement.

If you just change the Library References, then the footprint info and links with Pcbnew are preserved. However, if you delete and adding new schematic symbols, then both the annotation and footprint links (timestamps) are lost, and it becomes a real nuisance to repair.

It is very kind and helpful !

I will proceed this way,
Thanks
Horacio

In your list the basic diode bridge does not exist in V5 libraries
V5 has D_bridge_*** with a few variants, you will have to experiment

The cache_lib is very important and is the reason you normally get the rescue library box pop up when you open an old project