U.K.-based bank HSBC experienced a glitch earlier this morning that locked some customers in the region out of their accounts, with customers then taking to Twitter and other social media to complain.

Detected early this morning, the glitch left the bank’s customers unable to get into their online or mobile bank accounts, with attempts to login reading, “your session has expired, please log back in.”

Affected customers noted the issue on Twitter, with concerns exacerbated by the fact that this is the last Friday of October, which meant many customers were without access to their salaries due to the glitch.

Customers tweeted:

@HSBC_UK You closed my local branch saying more people using mobile banking. But your not providing that are you? Now have more petrol costs

— Clive Morris (@crm_uk) October 27, 2017

.@hsbc @hsbc_uk Online banking & App unavailable on payday plus an error message straight from 2013- well done! ???? #hsbc pic.twitter.com/3ixIYo9Mab

— Christopher Phelps (@mr_protozoa) October 27, 2017

The problem was fixed by the bank in under an hour, according to HSBC — services are back up and running at the time of this reporting — but the initial cause of the issue is still unclear.

Read more at the Financial Times and BusinessInsider.