Mint 19 "Could not download all repository indexes"

[BADAX]

Two related issues here to a newbie that has enough experience to make me dangerous.

I installed Mint 19 from a fresh image last week, and have been trying to get WINE to show up in my applications menu ever since. I have tried installing from the software manager, but it says that it is already installed. I have tried installing from terminal, but it does not appear in applications. Now I may have messed up the update with all of this activity, as the update manager cannot automatically check for updates without intervention.

This is the error that I receive... "GPG error: https://dl.winehq.org/wine-builds/ubuntu xenial InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 818A435C5FCBF54AThe repository 'https://dl.winehq.org/wine-builds/ubuntu xenial InRelease' is not signed."

I can still update the list manually by simply clicking on the refresh button. At this point, I thought that I might ask someone who knows what to do before I have to reinstall the ISO. Everything else works just like my Mint 18 install did, but I need Wine for a couple of apps.

Thanks in advance for any effort that you give to this issue

[all41]

See this thread:
viewtopic.php?f=47&t=281426&p=1551755#p1551757

[sleeper12]

Remove the wine items in Software Sources: additional repos & authentication keys, Update the cache. Refresh in Update Manager.

[philotux]

LM 19 is based on Ubuntu 18.04 Bionic Beaver. You seem to have added the repository for Xenial, which is Ubuntu 16.04.

[zealbert]

Hello,
I also just got a similar message, saying "could not download all repository indexes", along with the following message:

"An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://dl.google.com/linux/earth/deb stable Release: The following signatures were invalid: EXPKEYSIG 1397BC53640DB551 Google Inc. (Linux Packages Signing Authority) <linux-packages-keymaster@google.com>Failed to fetch http://dl.google.com/linux/earth/deb/di ... elease.gpg The following signatures were invalid: EXPKEYSIG 1397BC53640DB551 Google Inc. (Linux Packages Signing Authority) <linux-packages-keymaster@google.com>Some index files failed to download. They have been ignored, or old ones used instead."

I am not very computer savvy, can anybody tell me what to do?
Thanks

[Moem]

I am not very computer savvy, can anybody tell me what to do?

Certainly! Three things:
- In cases like this, look for threads that seem to be about the same thing and are from yesterday or today. In this case, you'll find several on the first page, if you use the chronogical forum view found in the Quick Links list (top left of page).
- In this specific case, a search for 'google signature invalid' will lead you to several threads that give a solution. Here's one. Here's another.
- In general, please do not reuse existing threads. Just start a new one. This one is not about the same issue as you're having anyway.