Adobe's Creative Cloud is in the midst of a massive outage that has lasted for more than 18 hours and has affected users throughout the United States, Europe and Asia.

Subscribers to Creative Cloud — which includes Photoshop, Acrobat, Lightroom, InDesign and other apps — have been unable to access their accounts, download applications or make purchases or upgrades. Adobe has identified the cause of the issue but has not yet revealed what it is.

See also: These 11 Apps Will Supercharge Your Personal Life

An Adobe spokesperson confirmed to Mashable that the Adobe login is down and that the company is working on a fix, but did not offer a timeframe for when services would be back online.

Adobe login is currently offline, impacting access to some Adobe services. We apologize for the disruption. We have identified the cause and are working to restore the service as quickly as possible. We will share updates on Twitter at @AdobeCare.

The company's status page now lists desktop apps down as well.

It appears the problems began as early as Wednesday afternoon, when Adobe first reported "an issue with purchasing Creative Cloud subscriptions" on its status page. Issues with downloading applications, admin accounts, Adobe IDs and logging into Creative Cloud accounts were reported soon after.

We're currently experiencing an outage affecting user's ability to sign in to our services. We are working on a fix- stay tuned — Adobe Customer Care (@AdobeCare) May 14, 2014

At the time of this writing, desktop applications that are already installed are up and running, according to Adobe — but downloads, web files, user and admin accounts are all down.

A message on the Creative Cloud website says the site is "currently undergoing maintenance."

Adobe announced it would move its flagship Creative Suite software to a cloud-based subscription-only model last spring, which sparked outrage from many users, particularly those in rural areas with less reliable Internet access. Outages weren't really an issue before it moved to the cloud, since apps and files were stored locally.

Upset users are complaining about the outage on Twitter, of course:

Let's all move to the #Cloud, it'll be great! Except when your service fails and 1000's of customers suffer. I'm looking @ u #CreativeCloud — Adrian Vinnicombe (@avinni) May 15, 2014

Absolutely disgusted by @adobe & @adobebc today, how can this be allowed to happen? As partners we need answers? @adobecare @creativecloud — Tom Edwards (@tomjamesedwards) May 15, 2014

Creative Cloud has experienced outages before, although nothing this widespread for an extended period.

Update 3:04 p.m. ET: Adobe Creative Cloud appears to be working again. We have successfully downloaded apps from the service, although web login is still offline. A tweet from Adobe indicates the company has made headway in addressing the problem.

We are making progress on restoring Adobe login services, and will share more info as it becomes available. — Adobe Customer Care (@AdobeCare) May 15, 2014

Update 5:55 p.m. ET: Adobe has posted a workaround for users who are unable to access their accounts due to the outage. Creative Cloud applications can currently be used in trial mode and Adobe has posted detailed instructions for doing so. In the meantime, the company is advising users not to sign out of their applications until the outage is over.

Please visit http://t.co/XgYE5WINPY if you are having difficulties using your #CreativeCloud applications during the outage — Adobe Customer Care (@AdobeCare) May 15, 2014

Update Friday, May 16, 2014, 1:20 p.m. ET: All of Adobe's Creative Cloud services are back online, including Adobe login. Adobe apologized for the outage, apparently caused by "a failure during database maintenance activity," in a blog post, but did not elaborate on the source of the problem.