[c] gdb: "No symbol table is loaded"

I keep getting this error mesage when trying to add a breakpoint in gdb.

I've used these commands to compile:

gcc -g main.c utmpib2.c -o main.o
and:
cc -g main.c utmpib2.c -o main.o
and also:
g++ -g main.c utmpib2.c -o main.o

I also tried "-ggdb" instead of "-g" and I still get that error message.

I then execute gdb:

$gdb

In gdb:

(gdb)exec-file main.o
(gdb)break 59
No symbol table is loaded. Use the "file" command.

You have to add extra parameter -g, which generates source level debug information. It will look like:

gcc -g prog.c

After that you can use gdb in common way.

Whenever gcc on the compilation machine and gdb on the testing machine have differing versions, you may be facing debuginfo format incompatibility.

To fix that, try downgrading the debuginfo format:

gcc -gdwarf-3 ...
gcc -gdwarf-2 ...
gcc -gstabs ...
gcc -gstabs+ ...
gcc -gcoff ...
gcc -gxcoff ...
gcc -gxcoff+ ...

Or match gdb to the gcc you're using.

I met this issue this morning because I used the same executable in DIFFERENT OSes: after compiling my program with gcc -ggdb -Wall test.c -o test in my Mac(10.15.2), I ran gdb with the executable in Ubuntu(16.04) in my VirtualBox.

Fix: recompile with the same command under Ubuntu, then you should be good.

I have the same problem and I followed this Post, it solved my problem.

Follow the following 2 steps:

1. Make sure the optimization level is -O0
2. Add -ggdb flag when compiling your program

Good luck!