Metered connections are network connections that charge by volume of  
data transferred. That happens, for instance, with 4G modems, which I  
am using this week.

When one tethers a 4G mobile phone to a laptop, it is possible to  
select that the connection is metered, to avoid that Windows uses that  
link to download big but not so important data (e.g. updates).

I was unaware that OneDrive deactivates itself in metered connections  
even if I ask to synchronize data. When I opened a big file (the ones  
that OneDrive typically removes from the computer to save space and  
leaves in the cloud) Emacs got a system error that led to the behavior  
described before. It also happens with smaller files, I now realize,  
provided they were not cached in the computer.

It is possible to disable the "metered connection" status from the  
wifi network properties (Windows 10 and Windows 11 settings interface,  
not control panel). Then OneDrive spins up again and Emacs is left  
waiting until the file is downloaded, with no error message.

Juanjo

Eli Zaretskii <eliz@gnu.org> escribió:

>> Date: Wed, 13 Jul 2022 10:22:09 +0200
>> From: Juan Jose Garcia Ripoll <juanjose.garcia.ripoll@csic.es>
>> Cc: larsi@gnus.org, 56499@debbugs.gnu.org
>>
>> Apologies for the noise. I have found out that this problem is  
>> related to "metered connections".
>
> Thanks.  I was about to tell that I couldn't reproduce the problem on
> a machine where I have OneDrive set up.
>
>> On those
>> ones, Emacs cannot trigger opening of the file and is not capable  
>> of returning the right error message. Once
>> I disable the option "metered connection" from the network, Emacs  
>> operates as expected. I suspect this
>> cannot really be attributed to Emacs, except for the lack of error  
>> message in the first situation.
>
> Would you mind please telling more about the situation where it
> happens and about the symptoms?  Does this happen only with
> find-file-literally? does it happen only with large files? and what
> exactly are "metered connections" and how does one disable that
> option?
>
> The reason for the questions is that I'd like to describe the problem
> and the solution in etc/PROBLEMS.
> Thanks.
   Juan José García Ripoll

Instituto de Física Fundamental, CSIC
Calle Serrano 113b, Madrid 28006, Spain
Phone: (+34) 915616800 (dial 943107 when hearing the voice)
http://quinfog.iff.csic.es / http://juanjose.garciaripoll.com