Syncthing crashing after updating to v1.27.1 / Windows 7 / runtime.asmstdcall()

Heads up, there is another bug :bug:
Today after automatically upgrading to v1.27.1 (last line in syncthing.log), Syncthing does not start again (Windows 7, x64, with service). Starting manually shows crash:

Exception 0xc0000005 0x8 0x0 0x0

        runtime/sys_windows_amd64.s:65 +0x75 fp=0x22fca0 sp=0x22fc80 pc=0x473dd5
rax     0x0
rbx     0x1a27f20
rcx     0x1a87ec0
rdi     0x7fffffdd000
rsi     0x22fea0
rbp     0x22fde0
rsp     0x22fc78
r8      0x0
r9      0x22fee0
r10     0x1a59a38
r11     0x21
r12     0x22fec0
r13     0x1
r14     0x1a27480
r15     0x0
rip     0x0
rflags  0x10293
cs      0x33
fs      0x53
gs      0x2b

Yeah, apparently the update to a newer point release of Go tickles an issue on Windows 7, which is unsupported since Go 1.21. (We switched to Go 1.21 with the Syncthing 1.24.0 release in August, but apparently things kept trucking for a while longer.)

Edit: Go 1.21.5 is the breakage point.


1.27.0 Working.

Вisabled auto update for now Auto Upgrade Interval (hours) = 0

ps I hope they fix it for Windows 7

This will not be fixed, sorry. Go, and hence Syncthing, now depends on some API that is just not present in Windows 7.


So how do we disable the auto-upgrade? My desktop runs Win-7 Pro, isn’t compatible with Win-10 or 11 and I don’t have the money to replace it.

Right, so usually that would be in the settings, but if the auto upgrade is too agressive you need to prevent it from doing that prior to start-up. What I would do is set an environment variable system-wide, which will always override the other config stuff. Here seems to be a guide on how to do that in Windows 7. You want to set a variable named STNOUPGRADE to the value 1 (or any non-empty value, afaik).

Okay - found it in the Config.xml…and we’re back up and running again. My Phone and Tablet thank you since they get fed from the ‘ancient’ desktop.

@Jason7107 I’m in the same boat (Win 7 SyncThing stopped). But I can’t find a 'config.xml. Could you elif please.

Please copy and paste %LOCALAPPDATA%\Syncthing into the address bar in Windows Explorer and press Enter.


after automatically upgrading this morning, Syncthing doesn’t work anymore with Windows 7. Reading this thread, I substituted the synthing.exe with the older syncthing.exe in the same folder, and it works again.

I can’t update my Operating System from W7 to a newer version these days (months!), so I cant’ let syncthing upgrade in the next future. My questions are:

  1. Will I have any trouble using Syncthing the next months without updating, e. g. security issues?

  2. My other two systems are linux-based. Should I deactivate autoupgrading under Linux, too, to avoid incompabilities between the Linux versions and the (not updated) W7 version?

  3. Any other hints do reduce trouble?

Many thanks in advance.

Best regards Wal

@Hank - file is located at C:\Users(user)\AppData\Local\Syncthing\config.xml

My Wordpad will edit it - search for “autoUpgrade” The whole line will read “autoUpgradeIntervalH # autoUpgradeIntervalH” where # is any non-zero number…mine was set to 12

Change that number to 0 and save.

Delete the ‘Syncthing.exe’ from the run directory and change ‘Syncthing.exe.old’ to ‘Syncthing.exe’ and you’ll be running the pre-update version.

I back-tracked the Syncthing on my desktop to 1.16.1 and it’s working with the Android version just fine. I don’t think it really cares what version is on what machine so long as the machines can see each other.

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It does care but unless you are running an extremely old version, you should be fine for the upcoming months, if not years.


That’s hard to predict. But your operating system isn’t getting security updates either any more, so this seems like an odd concern under the circumstances?


Touché! :wink:

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Perhaps syncthing could use some mechanism to identify what OS versions are compatible with future upgrades before those upgrades are done automatically. I have a system offline for a few days that is likely affected. Have to check up on what is that system is running. Yes I know windows 7 is beyond support. But we run some old hardware in some of these old systems that for valid reason is not easy to upgrade (and in some cases impossible…)

Anyway just a thought.

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I will assume quite a long time :slight_smile: until there are changes in the data exchange format, and they are quite stable.
An outdated version of resilio or syncthing (can’t remember which one specifically) worked for quite a long time on WinXP.
I’m leaving 1.27.0 and disabling updates. let’s see what the future holds.

@calmh Maybe we should add in the description of version 1.27.0 that it is the “last that works on Windows 7”.

Same problem. I’m syncing win10 to win7 and vice-versa, it no longer works . Is there a link to an older version to install to win7 machine or any other way?

The previous releases are available at Releases · syncthing/syncthing · GitHub

Click on the desired version and you’ll find the code as well as the executables for a dozen of platforms, including Windows. Just make sure to set --no-upgrade as argument, or it may automatically upgrade again.


I had to edit the config file to change the prerelease flag from true to false, saved then reopened St using an earlier version (1.27). The go into settings and told it to no longer do any updates (on W7 devices).

It will then sync as before

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