Jim M

Sorry, we would not have any old sites of yours. The Account -> My Attachments are files which you uploaded here on our community, such as screenshots in topics here, etc... They would not be backups of your communities.
We do not manage backups for self-hosted communities. We do manage backups for our Cloud communities but you would need to submit a support request to obtain those, there is no automated process.

There would be no way to just say field "has data". There would need to be some value there.

Unfortunately, this is an issue with your custom theme, please create a new theme by going to ACP -> Customization -> Themes -> Create New and then set that as your default theme. You will then see your login fields are back. 

I'm afraid, only the default browser on the device is currently supported. For Android, this would be Chrome. I would suggest using Chrome and letting us know if you still have issues.

Sorry, we only provide the latest release. However, I am a little confused on why you would need 4.7.3 as it sounds like you want to upgrade to PHP 8, is that correct? If so, you can just switch to PHP 8 and perform a manual upgrade.
Here's information about doing a manual upgrade: 
 

This is a partial query it appears. Is that the full log?
 
That would likely indicate that there is an error in a custom or third party application/plugin/theme. You would want to disable those and then switch an unmodified theme to test.

If this happens in the future or anyone else needs info, you can enable recovery mode as detailed in the following guide
 

I have just responded to the email we received a few minutes ago from you. Sorry, I'm afraid, this was the only email on your account. However, please see the email and we can help you get your account cancelled.

This is the Edge browser, I'm afraid, not our software 😉 .
Can click ctrl+shift+v to paste the URL itself.

We have assisted you in the account email you submitted.

It's in the language system: 
 

Once you use any menu item, it is not present to be used again. You would need to use the "External Link" option to do what you want to here.
If you would like to see changes to this in the future, please leave your suggestion in our Feature Suggestion forum.

This is called the "Topic Summary" you can adjust settings or disable it in ACP -> Community -> Forums -> Settings

The software would need to live in the same folder so whatever you want to name that folder which makes sense for your usage you can do.
It looks like you do have something at your root domain so you would not be able to put the software there unless you were to remove that.

I would recommend reverting any changes you've done in this area as it seems to be the root of your problem.

This is a known issue; a manual upgrade is required as mentioned here:
 

Thanks! This is a known issue which will be fixed in a upcoming release. To get past it now, you can perform a manual upgrade.

If they are appearing in the Email Error log, that would indicate an issue with connecting your SMTP server rather than the software. As you can see there is an error of 421 Service not available... That is coming from your SMTP server. Please reach out to your email provider for assistance.

Anyone can create events in the application. Please ensure that your member groups have proper permissions to do so. 
 
 

You will want to ensure that they are also the latest versions and unmodified. To confirm, you may wish to upload a fresh set of files from the Client Area and extract them to your computer. Once done, upload the contents of the "ips_****" folder to your server, overwriting what is there.

If you disable access to your community for a group, as you've done here, this is effectively banning that group from your site as you are stating they shouldn't have access to your community. If you believe that this sends the wrong connotation for your users, you can change the message here for all groups/users who don't have access and would view this permission denied message (keep in mind this would be for this use case and actual banned members, etc...) by changing the language string.
To read more about changing language strings, please read:
 

Simply login to the client area and download a full package of software, much like you would if doing a fresh install, and unzip the archive to your computer. It will create a folder named "ips_xxxxx" where xxxxx is a random string of characters. Then use an FTP client such as Filezilla and upload the contents of the ips_xxxxx folder (not the folder itself) to your forum main directory, overwriting when prompted and making sure all files transfer without error.
These are just the core files which run the software, it will not impact your data.

Yes. 

The checkbox there is controlled in ACP -> Members -> Notifications -> Newsletter.
If you are looking how you initiate and send email to these users, this would be in ACP -> Members -> Bulk Mail.

They would simply need a password assigned to their account either by you doing this in the ACP or have them reset their password via your sign in page.