The Entertainment Software Association (ESA) has apologized for mistakenly issuing Digital Millennium Copyright Act (DMCA) takedown notices for Dying Light mod files shared online this weekend, saying the requests were issued erroneously by a third-party vendor on the organization's behalf.

The controversy began Saturday when at least two MediaFire users were notified that Dying Light modification files they posted online had been taken down for violating the sharing site's Terms of Service. Those takedown notices identified the ESA as the complainant, referred to "copyright infringement" as the reason and directed readers to an "antipiracy" e-mail address. This happened despite the fact that both files had nothing to do with piracy and merely modified the game's visuals.

The timing of the takedowns was suspicious, coming alongside the release of a mod-blocking patch from Dying Light developer Techland late Friday. The patch notes for Dying Light Update 1.21 state that the patch "block[s] cheating [in the game's online PvP "Be the Zombie" mode] by changing game’s data files." Reports on reddit and elsewhere, though, suggest the patch is also preventing modders from making changes to weapons and items in the single-player campaign.

Many observers linked these two events together, suspecting that ESA member and Dying Light publisher Warner Bros. was going overboard in using the DMCA in order to stop any online distribution of mod files on top of the patch's technical fix. The ESA, which represents many of the game industry's biggest publishers, tells Ars that's not the case.

"ESA was notified this morning that potentially erroneous DMCA notices had been transmitted by one of its vendors," the organization told Ars. "Upon further review, it was determined that the notices should not have been sent and retractions were issued immediately. We regret any inconvenience and have taken steps to avoid similar situations in the future."

Meanwhile, Techland said that the latest patch's impact on single-player modding was merely an unintended side-effect of the system it put in place to stop online cheaters. The company added that offline modding will be restored as soon as possible.

"Creating obstacles for modders has never been our intention," Techland said in a statement provided to Ars Technica. "We are now working on a quick patch that will re-enable common tweaks while stopping cheating in the game's multiplayer mode.

"At Techland, we have always supported the mod community and loved seeing how our own game can be changed by the players. A big part of the original Dead Island's success was the passion and creativity of mod-makers from our community. We want the same for Dying Light."