My host recently decided to update Apache PHP module and send mass email to all existing customers that this will happen and that we should update our sites (the ones with PHP) with some code changes.

That's when the hell broke loose. Every single site owner was hurried to update the code because if he didn't his PHP code on the site wouldn't work anymore. Since the system was obviously overloaded I couldn't get to access trough FTP for more than 10 hours.

There was a proper notification one day before this but how stupid were they not to predict people jamming the connection.

Imagine if someone's site lost thousands of $ because of them.

Couldn't they run both versions?

Depends on the module I guess. If the OP is talking about upgrading the server from version 4 to version 5 of PHP, then this should have been done last year at the latest. PHP 4 is EOL and considered a risk to run on any system. Anyone still using version 4 and collecting credit card or sensitive information should be shot!

So I guess - what module was updated by your host, and why didn't they give more time than just 24 hours?

Like Conor said, 24 hours doesn't seem like a long enough window to allow its clients to make the necesary updates.

i will think twice before update somethings

Yep, 24 hours hours for such an update is not enough time. 72 hours wouldve been enough time to warn everyone.

I know when we did major updates we actually gave MONTHS in advance if possible.

We actually had S.M.A.R.T. drive errors the other day on one of our machines - and while we make backups, we don't want to just move a site overnight and expect that they can update their DNS quickly etc (some people don't use our DNS) - so we notify customers that there's potential hardware issues that we want to move them to a new machine etc - give them up to 7 days for the move. They get a special link to schedule a move with our admins, and if they haven't submitted the reqeust within the allotted time, then we move them manually and resend notifications etc.

There's more to an upgrade of software or a site move than what can be expected some times. Whenever possible TIME is what people need, and notifying people on a FRIDAY and dong the things SUNDAY does not count as 48 hours - that's the weekend, most people would have missed the notice.

Even when we do cPael updates or Apache updates which could result in up to 5 minutes of downtime while a system reboots, we give a MINIMUM 48 hours notice just so people know we may be offline for 5 minutes.

Communication is key - if you're host isn't doing that, time to move to a new host!

I can imagine your frustration! I agree with handsonhosting that they should have given you much more notice than 24 hours. You know that they knew it was going to happen well before then!

Sorry to hear :/ Usually they should give a weeks warning at least.