It’s now September, and as anticipated, the second Twitpocalypse is nearing. In fact, Twitter now says it knows the date it will hit: This Friday, September 11.

For those who don’t recall, the Twitpocalypse is the name given to the anomalies that occur when tweet ID (each tweet is assigned a unique ID) hit the integer walls. The first Twitpocalypse occurred back in June when the 32-bit signed integer number was hit. This second one is occurring because 32-bit unsigned integer wall is about to be hit.

Now, to be clear, any app that did the recommended update to 64-bit numbers will not be harmed by this latest crisis. But apps that didn’t will start to break on Friday, as they fail to process the tweet ID 4,294,967,296.

Twitter is artificially pushing the tweet IDs up to this number, to control when they hit it. That’s why the September 11 date is so far off from twitpocalypse.com’s countdown. Twitter’s Platform Lead Alex Payne posted the following today:

As mentioned previously, the Twitter operations team will artificially increase the maximum status ID to 4294967296 this coming Friday, September 11th. This action is part of routine database upgrades and maintenance.

If your Twitter API application stores status IDs, please be sure that your datastore is configured to handle integers of that size. Thanks.

A large-scale crisis was largely averted the first time around, but a number of popular Twitter iPhone apps were broken for weeks, as they waited for updates to be pushed through the App Store approval process.

Consider yourself warned.