As previously announced, developers NetherRealm and High Voltage Software rolled out a substantial patch for the Windows PC version of Mortal Kombat X today. While the patch promised "huge improvements" for the PC version, bringing it to parity with its console counterparts, it also came with a major bug.

Shortly after rolling out the patch through Steam, players reported that the new update was deleting their save data. Players found that unlocked characters were no longer available and all of their progress in the game's Krypt, a dungeon crawler-like game stuffed with unlockables, had been reset.

Publisher Warner Bros. has since pulled the patch from Steam and said it's investigating the issue.

"We are temporarily removing the patch until we can pinpoint the cause of save data loss," an update posted to Steam reads. "We are actively working on this and will keep everyone posted as we work towards a fix. We sincerely apologize for this disruption."

The update for Mortal Kombat X included a long list of changes, tweaks and improvements, including fixes for a number of crashes and performance issues related to the PC version. NetherRealm said earlier this week that it's working to improve the game's online networking code and address player concerns.

Mortal Kombat co-creator Ed Boon appeared on NetherRealm's livestream yesterday, saying, "We are slaving to try to get [the game] as good playing as possible. There's no way we consider ourselves content with where we are as far as the online experience."

For more on Mortal Kombat X, check out Polygon's review.