Update: As outlined in our original story below, a number of Dark Souls Remastered players have reported save file corruption since its PC launch last month. Yesterday, Bandai Namco identified popular antivirus applications Bitdefender and Windows Defender as the likely offenders, and provided a fix. The former has now replied to PC Gamer with a workaround. 

"[Following yesterday's story] We found out that the Dark Souls caches (saved progress in the game) are not altered, but the process that tries to access them is being blocked from saving or loading because it is not signed by a trusted certificate," a Bitdefender representative tells us via email. "The Bitdefender anti-ransomware feature Safe Files protects different user files from being altered by applications that are not considered legitimate. 

"The folders that are being monitored by Bitdefender are listed in our product here: Protection tab > View Features > the Safe Files tile."

Bitdefender says that in order to allow Dark Souls to access and modify the saved files that are stored in a folder protected against ransomware attacks, players should add the game's executable as 'Allowed' in the Application Access area or remove the Documents folder from Protected folders.

Bitdefender adds: "The majority of the applications are signed with trusted certificates, so the user will not run into issues like the one detailed by you.

"The output generated by games or other programs should be excluded from this additional safety layer. We will use this feedback to make our users more aware about how they should secure their files using this feature."

Our original story follows.  

Image credit: Reddit user Empathy_Crisis. 

Original story: 

As detailed throughout the Dark Souls subreddit, Dark Souls remastered players using both Bitdefender and Windows Defender have reported corrupted save files, indefinite load times and instances where cloud sync services—Google Drive, for example—interprets save files as "in use" and therefore makes them inaccessible.  

It seems the problem has been kicked up to publisher Bandai Namco. Under the headline "Warning: Bitdefender and Windows Defender may treat DS:R saves as corrupted files", here's Dark Souls community manager Izmar:

Salutations, Chosen Undead

Based on feedback that we have received from the community, we must warn you that some popular anti-virus software may damage Dark Souls: Remastered save files, or treat those files as if they were corrupted. 

Additionally, if your computer uses a cloud sync service (e.g., Google Drive or Dropbox), it is possible for save files to be interpreted as "in use" by the system, rendering them inaccessible by the game.

In both cases, if you run into this problem, please take a moment to exclude your save files from being managed by your sync services and/or your anti-virus software.

Thank you for your kind attention.

For what it's worth, I myself use Avira Antivirus and am around halfway through a DS:R NG+ save without issue. Consider this a PSA if you use the aforementioned software. 

While you're here, this from Shaun is great: Is Dark Souls Remastered worth playing without its former mystery?

 Image credit: Reddit user Empathy_Crisis.