Unexpected difficulties with upgrade <SOLVED>

[plusnetuser]

Version: LMDE Update Pack 6, 64bit, Mate version

(Please assume I'm a bit "green", as I never had a chance to use computers before I retired, and my on-screen vision is not 100%))

A few weeks ago, I used "update manager" and had a number of unexpected results, some of which I've managed to correct, but some things like Firefox and Pluma are not working fully correctly; the ordinary terrminal, that uses sudo, has somehow got lost, though I still have the root terminal that launches with the password. I'd like to do another update, to see if this will repair the glitches.
However, when I try to use update manager again, it says there are about 70 packages to download, but always stalls in the 30s, and gives this error message:

Failed to fetch http://lmde-mirror-fr-1.wedrop.it/latest/dists/testing/main/binary-amd64/Packages 403 Forbidden [IP: 37.59.41.108 80]
Failed to fetch http://lmde-mirror-fr-1.wedrop.it/latest/dists/testing/contrib/binary-amd64/Packages 403 Forbidden [IP: 37.59.41.108 80]
Failed to fetch http://lmde-mirror-fr-1.wedrop.it/latest/dists/testing/non-free/binary-amd64/Packages 403 Forbidden [IP: 37.59.41.108 80]
Failed to fetch http://lmde-mirror-fr-1.wedrop.it/latest/dists/testing/main/binary-i386/Packages 403 Forbidden [IP: 37.59.41.108 80]
Failed to fetch http://lmde-mirror-fr-1.wedrop.it/latest/dists/testing/contrib/binary-i386/Packages 403 Forbidden [IP: 37.59.41.108 80]
Failed to fetch http://lmde-mirror-fr-1.wedrop.it/latest/dists/testing/non-free/binary-i386/Packages 403 Forbidden [IP: 37.59.41.108 80]
Failed to fetch http://lmde-mirror-fr-1.wedrop.it/latest/security/dists/testing/updates/main/binary-amd64/Packages 403 Forbidden [IP: 37.59.41.108 80]
Failed to fetch http://lmde-mirror-fr-1.wedrop.it/latest/security/dists/testing/updates/contrib/binary-amd64/Packages 403 Forbidden [IP: 37.59.41.108 80]
Failed to fetch http://lmde-mirror-fr-1.wedrop.it/latest/security/dists/testing/updates/non-free/binary-amd64/Packages 403 Forbidden [IP: 37.59.41.108 80]
Failed to fetch http://lmde-mirror-fr-1.wedrop.it/latest/security/dists/testing/updates/main/binary-i386/Packages 403 Forbidden [IP: 37.59.41.108 80]
Failed to fetch http://lmde-mirror-fr-1.wedrop.it/latest/security/dists/testing/updates/contrib/binary-i386/Packages 403 Forbidden [IP: 37.59.41.108 80]
Failed to fetch http://lmde-mirror-fr-1.wedrop.it/latest/security/dists/testing/updates/non-free/binary-i386/Packages 403 Forbidden [IP: 37.59.41.108 80]
Failed to fetch http://lmde-mirror-fr-1.wedrop.it/latest/multimedia/dists/testing/main/binary-amd64/Packages 403 Forbidden [IP: 37.59.41.108 80]
Failed to fetch http://lmde-mirror-fr-1.wedrop.it/latest/multimedia/dists/testing/non-free/binary-amd64/Packages 403 Forbidden [IP: 37.59.41.108 80]
Failed to fetch http://lmde-mirror-fr-1.wedrop.it/latest/multimedia/dists/testing/main/binary-i386/Packages 403 Forbidden [IP: 37.59.41.108 80]
Failed to fetch http://lmde-mirror-fr-1.wedrop.it/latest/multimedia/dists/testing/non-free/binary-i386/Packages 403 Forbidden [IP: 37.59.41.108 80]

Similar, but fewer, lines like this also appear if I try to download individual software

I'd be grateful for advice if I can correct this, or whether you'd recommend I reinstall the OS from scratch

[GeneBenson]

Hi plusnetuser,

Never had this myself. But you could try the following. In a terminal (Root terminal will work) enter the following:

Code: Select all

mint-choose-debian-mirror

This will try to find the fastest mirrors for updates. Hopefully it will find ones that actually work.

[plusnetuser]

Thank you, GeneBenson!

I tried your advice, and after choosing the first mirror it suggested, it completed the update manager process, and says the system is up to date.

It seems that the problem lay in the second tab of edit/software sources, "other software" - which was set to a source returning a 403 error
(I'm afraid I don't know enough to tell why it was set to this source in the first place, or whether "other software" would be needed very often))
Anyway it's now corrected - so I appreciate the help.

It's too early to tell whether this will solve a few other odd effects - but those I can put up with. Hopefully it will avoid the need to reinstall (which was the main reason I chose a semi-rolling distribution.)
I'm not a particularly experienced user, but despite the advice that LMDE may be less suitable for non-technical users, I've found it the most reliable and consistent distribution that I've tried, and I'd like to stay with it

Thanks again