Hi I recently upgraded the OS from Ubuntu18.04 to Ubuntu20.04. Now I notice that when I do sudo apt-get upgrade, I have packages kept back:

The following packages have been kept back:

  build-essential cpp g++ gcc gfortran liblapack-dev liblapack3

0 upgraded, 0 newly installed, 0 to remove and 7 not upgraded.

I tried the methods mentioned here.
To resolve this I tried

sudo apt-get dist-upgrade

but the output is the same as before.

I also tried
sudo aptitude full-upgrade
and the solution is also to keep the packages at their current version. The output is the following:

The following NEW packages will be installed:

  cpp-9{ab} g++-9{ab} gcc-9{ab} gfortran-9{ab} libasan5{ab} libgcc-9-dev{ab} libgfortran-9-dev{ab} libgfortran5{ab} libstdc++-9-dev{ab} 

  libubsan1{ab} 

The following packages will be upgraded:

  build-essential cpp g++ gcc gfortran liblapack-dev liblapack3 

7 packages upgraded, 10 newly installed, 0 to remove and 0 not upgraded.

Need to get 44.5 MB of archives. After unpacking 170 MB will be used.

The following packages have unmet dependencies:

 cpp-9 : Depends: gcc-9-base (= 9.3.0-17ubuntu1~20.04) but 9.4.0-1ubuntu1~18.04 is installed

 libgfortran-9-dev : Depends: gcc-9-base (= 9.3.0-17ubuntu1~20.04) but 9.4.0-1ubuntu1~18.04 is installed

 libasan5 : Depends: gcc-9-base (= 9.3.0-17ubuntu1~20.04) but 9.4.0-1ubuntu1~18.04 is installed

 libstdc++-9-dev : Depends: gcc-9-base (= 9.3.0-17ubuntu1~20.04) but 9.4.0-1ubuntu1~18.04 is installed

 libubsan1 : Depends: gcc-10-base (= 10.2.0-5ubuntu1~20.04) but 10.3.0-1ubuntu1~18.04~1 is installed

 g++-9 : Depends: gcc-9-base (= 9.3.0-17ubuntu1~20.04) but 9.4.0-1ubuntu1~18.04 is installed

 libgfortran5 : Depends: gcc-10-base (= 10.2.0-5ubuntu1~20.04) but 10.3.0-1ubuntu1~18.04~1 is installed

 gcc-9 : Depends: gcc-9-base (= 9.3.0-17ubuntu1~20.04) but 9.4.0-1ubuntu1~18.04 is installed

 gfortran-9 : Depends: gcc-9-base (= 9.3.0-17ubuntu1~20.04) but 9.4.0-1ubuntu1~18.04 is installed

 libgcc-9-dev : Depends: gcc-9-base (= 9.3.0-17ubuntu1~20.04) but 9.4.0-1ubuntu1~18.04 is installed

The following actions will resolve these dependencies:



      Keep the following packages at their current version:

1)      build-essential [12.4ubuntu1 (now)]                

2)      cpp [4:7.4.0-1ubuntu2.3 (now)]                     

3)      cpp-9 [Not Installed]                              

4)      g++ [4:7.4.0-1ubuntu2.3 (now)]                     

5)      g++-9 [Not Installed]                              

6)      gcc [4:7.4.0-1ubuntu2.3 (now)]                     

7)      gcc-9 [Not Installed]                              

8)      gfortran [4:7.4.0-1ubuntu2.3 (now)]                

9)      gfortran-9 [Not Installed]                         

10)     libasan5 [Not Installed]                           

11)     libgcc-9-dev [Not Installed]                       

12)     libgfortran-9-dev [Not Installed]                  

13)     libgfortran5 [Not Installed]                       

14)     liblapack-dev [3.7.1-4ubuntu1 (now)]               

15)     liblapack3 [3.7.1-4ubuntu1 (now)]                  

16)     libstdc++-9-dev [Not Installed]                    

17)     libubsan1 [Not Installed]      



           

Can someone give me some suggestions? Thanks!