World Cup fever and planned maintenance to tweak Twitter’s infrastructure combined to issue the microblogging service a yellow card, with vice president of communications Sean Garrett posting on the Twitter Blog that June has been its worst month since last October “from a site-stability and service-outage perspective.”

Garrett wrote:

Last Friday, we detailed on our Engineering blog that this is going to be a rocky few weeks. We’re working through tweaks to our system in order to provide greater stability at a time when we’re facing record traffic. We have long-term solutions that we are working toward, but in the meantime, we are making real-time adjustments so that we can grow our capacity and avoid outages during the World Cup.

As we go through this process, we have uncovered unexpected deeper issues and have even caused inadvertent downtime as a result of our attempts to make changes. Ultimately, the changes that we are making now will make Twitter much more reliable in the future. However, we certainly are not happy about the disruptions that we have faced and even caused this week and understand how they negatively impact our users.

Record traffic and unprecedented spikes in activity are never simple to manage. However, we were well aware of the likely impact of the World Cup. What we didn’t anticipate was some of the complexities that have been inherent in fixing and optimizing our systems before and during the event.

Over the next two weeks, we may perform relatively short planned maintenance on the site. During this time, the service will likely be taken down. We will not perform this work during World Cup games, and we will provide advance notification.

For real-time updates on site outages or major issues, you can go to our Status blog. For most other problems that you may be having with Twitter, follow @Support.