self hosted Bitwarden creating two similar .BAK files each night - one minute apart

[roblatour]

Steps To Reproduce

wait until Bitwarden's nightly backup happens then look at backup folder using MS explorer

Expected Result

Each night my selfhosted version of Bitwarden should only produce one .BAK file

Actual Result

Each night my selfhosted version of Bitwarden - running on docker under Windows docker for Desktop creates two similar backup files - a minute apart. I've done a hex compare on them and they are mostly, but not entirely, the same. A screen shot taken from the file listing window of MS explorer is included below.

Screenshots or Videos

Additional Context

No response

Build Version

Server Installed 2025.9.0 Server Latest 2025.9.0 Web Installed 2025.9.0 Web Latest 2025.9.0

Environment

Self-Hosted

Environment Details

W11 - Docker for Desktop

Issue Tracking Info

• I understand that work is tracked outside of Github. A PR will be linked to this issue should one be opened to address it, but Bitwarden doesn't use fields like "assigned", "milestone", or "project" to track progress.

[bitwarden-bot]

Thank you for reporting this issue! We've added this to our internal tracking system.
ID: PM-26138

[jtodddd]

Hi there,

This has been escalated for further investigation. If you have more information that can help us, please add it below.

Thanks!

[stopflunky]

Hi, i tried to resolve your issue but my installation don't gave me this problem. After some research i saw that maybe your problem is under /util/MsSql/backupd-db.sh

If you notice BACKUP_INTERVAL is 'nex day'
I tried to do myself a backup manually and setting BACKUP_INTERVAL to 'next day'. My container said me that 'next day' is not supported. Maybe your installation once a day facing this file to doing a backup incurs in some issue i can't explain.

By the way, i tried to replace 'next day' with 'next_day' or 'tomorrow' which are supported.
So, please change 'next day' in 'next_day' or 'tomorrow' and rebuild your container.

[roblatour]

thank you, i'm not sure where I would change that.
in am running bitwarden self hosted under docker for windows with access via the docker desktop for windows icon
to update the instance I use:
.\bitwarden.ps1 -updateself
.\bitwarden.ps1 -update
so I don't know if I changed it that it would persist?

[stopflunky]

ok if you use Docker Desktop via windows you can select the container of the database, that is called bitwarden-mssql or something similar, after you select the mssql container go to the exec option on the top menu. A bash shell will appear you, if you type a 'ls' comand you'll see the backup-db.sh and you can change if you want that setting of BACKUP_INTERVAL.

However i had an issue with my backup too. My daily backup is executed every 3days and not everyday. Now i try the procedure i wrote up for you. Let's see if my error will resolve.

If we find that the issue is the attribute of BACKUP_INTERVAL i will do a pull request to this repo and after you'll update your local version as always with .\bitwarden.ps1 -update

[roblatour]

thank you, I was able to find the backup-db.sh file.

For what its worth, I ran it through an AI and it recommended the following:

backup-db.sh

However, I haven't tested it. Would you like me to?

[roblatour]

i have replace the backup-db.sh on my system with the one above.

I should know tonight around 8pm (EST) if it worked or not for today, and again tomorrow at that time if it will continue to work.

Will post back here with results.

[roblatour]

well, it ran twice this evening. I may have however done something wrong when moving the new file over. Will try again for tomorrow night.

[roblatour]

it ran twice again tonight, with the updated shell file.

I ran the backup shell thru Copilot AI and it changed the code to run at local midnight (instead of UTC) midnight and promised this would fix the problem.

I've update the shell and will know tomorrow when I wake up.

Here is the revised shell:

backup-db.sh

[stopflunky]

the only change i've done is the first line on the script:

BACKUP_INTERVAL=${BACKUP_INTERVAL:-tomorrow}

[roblatour]

fair enough.

When I checked my results (using the script above) nothing was backed up. Apparently, there were some Windows new line characters in the file that I needed to remove before it would run.

Which I've now done, here:

backup-db.sh

Regardless, I now have your revised backup-db.sh running on my system (the one containing -tomorrow).

I will post back with my results after 8pm tonight.

Also, I noticed when testing with your updated version (and my revised version above) - both wait until the specified time to create the backup. I know this is by design, but the result of which is that I've been a couple days now with no backups and that got me thinking ...

It would perhaps be better to create the backup when the service starts, and then every 24 hours after that. While it wouldn't matter much to me, others may not be running bitwarden 7/24 (and thus may not be getting daily backups if the backup is triggered when their system is not running) or may otherwise benefit from a new backup being created each time the service has started - which I suspect for most people would be only when they upgrade. Anyways, something to think about.

Again, I will post back with my results after 8pm tonight.

Thanks for your help with this.

[roblatour]

so the backup-db.sh file with the 'tomorrow' in it created a backup at 7:59 pm and 8:00 pm tonight.

I have now replaced it with the ai generate backup.-db.sh file (link above) which should create a backup at midnight tonight.

I will post back here with the results in the morning.

[roblatour]

its now after midnight where i am, no backup was made with the ai shell file. I am going to take a break from this for a while.

edit: 3 days later, I'm back at it - have made a change and will know after midnight if it worked and will post back here

[roblatour]

Finally!

The following shell worked, created one backup at 8:00 pm (EST) - which is midnight UTC.

backup-db.sh

It was created with the help of MS Copilot, using the GPT-5-Codex (Preview) agent.

Also, here is how I set it up to run on my system:

assumes the updated backup-db.sh file has already been moved to c:\temp
in powershell:

cd "C:\temp"

the following removes any Windows new line characaters:
(Get-Content "backup-db.sh" -Raw) -replace "rn","`n" | Set-Content "backup-db.sh" -NoNewline

copy the updated shell file to the bitwarden-mssql container:
docker cp 'C:\temp\backup-db.sh' bitwarden-mssql:/backup-db.sh

docker exec -it bitwarden-mssql sh

double check the file is where you expect it to be:
more backup-db.sh

optionally remove the Window characters here instead of above
sed -i 's/\r$//' backup-db.sh

ensure the shell can be executed
chmod +x backup-db.sh
exit

stop and start the bitwarden-mssql container
docker restart bitwarden-mssql

confirm the shell is running
in powershell
docker exec -it bitwarden-mssql sh
ps -efa

there should be a line that says "/bin/sh /backup-db.sh loop" under CMD

It would be nice is someone else could take a look / test the shell above, and if it is ok send it forward for update in the next release.