Tribulations of Upgrading Ubuntu from 16.04 LTS to 20.04 LTS

[Nick]

Originally Posted by EdH

If anyone has any thoughts about the Internet issue, I wouldn't mind reading them. I "think" I have all the rest under control, even if it is going to take a long time to get these machines factoring again.

I don't use Ubuntu but the rule of thumb with IP problems is that they are either routing problems or filtering problems.
What does the routing table look like?

[EdH]

Originally Posted by Nick

I don't use Ubuntu but the rule of thumb with IP problems is that they are either routing problems or filtering problems.
What does the routing table look like?

The only difference is a "Metric" value:

Working machine:

$ route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.0.1     0.0.0.0         UG    100    0        0 eno1
169.254.0.0     0.0.0.0         255.255.0.0     U     1000   0        0 eno1
192.168.0.0     0.0.0.0         255.255.255.0   U     100    0        0 eno1

Non-working machine:

$ route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.0.1     0.0.0.0         UG    20100  0        0 eno1
169.254.0.0     0.0.0.0         255.255.0.0     U     1000   0        0 eno1
192.168.0.0     0.0.0.0         255.255.255.0   U     100    0        0 eno1

But, I don't know what that signifies.

"ip route" shows the same values:

Working machine:

$ ip route
default via 192.168.0.1 dev eno1 proto static metric 100 
169.254.0.0/16 dev eno1 scope link metric 1000 
192.168.0.0/24 dev eno1 proto kernel scope link src 192.168.0.96 metric 100

Non-working machine:

$ ip route
default via 192.168.0.1 dev eno1 proto static metric 20100 
169.254.0.0/16 dev eno1 scope link metric 1000 
192.168.0.0/24 dev eno1 proto kernel scope link src 192.168.0.44 metric 100

[EdH]

On the good side, I have 18 (17) of 20 original machines fully upgraded with all the latest of everything. (One of the 18 didn't fully upgrade the OS.) But, it is fully working for all the factoring packages.

On the bad side, the two that stopped being able to access the Internet have not gotten any better and I haven't been able to determine why. Everything appears to point to them working correctly. However, I don't have any 18.04 machines to compare them directly with ATM.

I'm looking at two approaches:

1. I'm upgrading a 16.04 machine to 18.04 to see if I can match its settings better to the two that don't work.

2. I'm exploring the idea of setting up a proxy server on one of my other machines and using it to reach the Internet. I'm hoping that method will allow me to upgrade them to 20.04 and see if that fixes the Internet issue. Even if it doesn't solve the issue, if I can get these machines fully upgraded for all the packages and they remain able to work within the LAN, all should be good.

For the most part, once I got into a routine, all the upgrading went well for the majority of the machines. I was even able to just "svn up" and recompile some of the packages without starting from scratch although other packages didn't work that way, even after "uninstalls" and "make clean" attempts.

@Xyzzy: The package manager approach sounds good on the surface, but I like to be able to catch all the latest revisions for YAFU, msieve,CADO-NFS, etc.

[EdH]

I'm not sure if this is the correct way to resolve the issue, but it worked.

I edited the /etc/systmed/resolved.conf file to replace the:

#DNS=

line, with:

DNS=192.168.0.1

However, the OS tells me something is amiss and it can't do a proper upgrade to 20.04. So, there is still trouble with these machines.

Might be time for a new install of the OS!

Edit: Just like magic! After I reported that they wouldn't upgrade properly, I returned to see what could be done. They both started the upgrades without any further complaint. . . yet!

[EdH]

This is an update to the Debian GUI issue I've mentioned in this thread and elsewhere.

I am happy to report that I have fixed the issue!

On all four Debian machines, (as root) I used:

apt-get install lightdm

and chose lightdm as the default display manager. Then I edited:

vi /etc/lightdm/lightdm.conf

to set up autologin, and all four Debian machines are running just like the Ubuntu ones.

After all the troubles for so long, the fix turned out to be extremely simple - get rid of Gnome Display Manager!

[xilman]

Originally Posted by EdH

After all the troubles for so long, the fix turned out to be extremely simple - get rid of Gnome Display Manager!

In my experience, getting rid of as much of Gome 3 as possible is a good thing.

[EdH]

Originally Posted by xilman

In my experience, getting rid of as much of Gome 3 as possible is a good thing.

I'm starting to realize that, finally.