Syncing stopped without any error

Support Android
1

My Windows computer (Syncthing v2.0.10) is in two-way sync with my Android phone (Syncthing v2.0.9). 2 days ago only the sync stopped working. There was one instance the computer received changes from the phone, not the other way. I suspected it was the wifi changed, but I haven’t been able to reproduce that.

Computer log

2025-10-10 08:51:40 INF syncthing v2.0.10 "Hafnium Hornet" (go1.25.1 windows-amd64) builder@github.syncthing.net 2025-09-23 12:46:31 UTC (log.pkg=main)
2025-10-10 08:51:41 INF Calculated our device ID (device=KEIORUM-QFPRO5W-EBJDUJT-QSJNKAM-QYMRH27-CL7QW6M-DBFG2XV-APZXHQV log.pkg=syncthing)
2025-10-10 08:51:41 INF Overall rate limit in use (send="is unlimited" recv="is unlimited" log.pkg=connections)
2025-10-10 08:51:41 INF Using discovery mechanism (identity="global discovery server https://discovery-lookup.syncthing.net/v2/?noannounce" log.pkg=discover)
2025-10-10 08:51:41 INF Using discovery mechanism (identity="global discovery server https://discovery-announce-v4.syncthing.net/v2/?nolookup" log.pkg=discover)
2025-10-10 08:51:41 INF Using discovery mechanism (identity="global discovery server https://discovery-announce-v6.syncthing.net/v2/?nolookup" log.pkg=discover)
2025-10-10 08:51:41 INF Relay listener starting (id=dynamic+https://relays.syncthing.net/endpoint log.pkg=connections)
2025-10-10 08:51:41 INF Using discovery mechanism (identity="IPv4 local broadcast discovery on port 21027" log.pkg=discover)
2025-10-10 08:51:41 INF Using discovery mechanism (identity="IPv6 local multicast discovery on address [ff12::8384]:21027" log.pkg=discover)
2025-10-10 08:51:41 INF TCP listener starting (address="[::]:22000" log.pkg=connections)
2025-10-10 08:51:41 INF Ready to synchronize (folder.label="Tất cả dữ liệu Quả Cầu" folder.id=yxqea-krdlp folder.type=sendreceive log.pkg=model)
2025-10-10 08:51:41 INF QUIC listener starting (address="[::]:22000" log.pkg=connections)
2025-10-10 08:51:41 INF GUI and API listening (address=127.0.0.1:8384 log.pkg=api)
2025-10-10 08:51:41 INF Access the GUI via the following URL: http://localhost:8384/ (log.pkg=api)
2025-10-10 08:51:41 INF Loaded configuration (name=OokerLaptop log.pkg=syncthing)
2025-10-10 08:51:41 INF Loaded peer device configuration (device=7AKM7QB name="Nhật — Vivo" address="[dynamic]" log.pkg=syncthing)
2025-10-10 08:51:42 INF Measured hashing performance (perf="146.23 MB/s" log.pkg=syncthing)
2025-10-10 08:51:43 INF Established secure connection (device=7AKM7QB connection.local=192.168.100.192:22000 connection.remote=192.168.100.144:22000 connection.type=tcp-client connection.lan=true connection.crypto=TLS1.3-TLS_AES_128_GCM_SHA256 connection.prio=10 connection.id=63CVOVUHIJOCU94MGTOMAD77D6 log.pkg=connections)
2025-10-10 08:51:43 INF New device connection (device=7AKM7QB address=192.168.100.144:22000 remote.name=SM-J610F remote.client=syncthing remote.version=v2.0.9 log.pkg=model)
2025-10-10 08:51:49 INF Established secure connection (device=7AKM7QB connection.local="[2405:4802:9386:ea90:a8b6:f765:b78e:cfcf]:22000" connection.remote="[2405:4802:9386:ea90:b76c:36e:1f44:5816]:22000" connection.type=tcp-client connection.lan=true connection.crypto=TLS1.3-TLS_AES_128_GCM_SHA256 connection.prio=10 connection.id=63CVP0L8JFL4S8FBNNCRPJPQ6A log.pkg=connections)
2025-10-10 08:51:49 INF Additional device connection (device=7AKM7QB address="[2405:4802:9386:ea90:b76c:36e:1f44:5816]:22000" count=1 log.pkg=model)
2025-10-10 08:51:55 INF Established secure connection (device=7AKM7QB connection.local="[fd00:db80::a8b6:f765:b78e:cfcf]:22000" connection.remote="[fd00:db80::a3f4:1957:23e1:af41]:22000" connection.type=tcp-client connection.lan=true connection.crypto=TLS1.3-TLS_AES_128_GCM_SHA256 connection.prio=10 connection.id=63CVP1AAVRNFG3Q2O82J7ET45S log.pkg=connections)
2025-10-10 08:51:55 INF Additional device connection (device=7AKM7QB address="[fd00:db80::a3f4:1957:23e1:af41]:22000" count=2 log.pkg=model)
2025-10-10 08:52:03 INF Detected NAT type (uri=quic://0.0.0.0:22000 type="Port restricted NAT" log.pkg=connections)
2025-10-10 08:52:03 INF Resolved external address (uri=quic://0.0.0.0:22000 address=quic://1.53.153.230:27606 via=stun.voip.aebc.com:3478 log.pkg=connections)
2025-10-10 08:52:06 INF Joined relay (uri=relay://172.93.219.156:22067 log.pkg=relay/client)
2025-10-10 08:52:11 INF New external port opened (protocol=TCP external="[21.104.45.153:43818]" local="[::]:22000" gateway=9137a101-8ccf-4d5b-8550-0386b9c0f37c/WANDevice/urn:upnp-org:serviceId:WANIPConn1/urn:schemas-upnp-org:service:WANIPConnection:1/http://192.168.100.1:5000/ctl/IPConn log.pkg=nat)
2025-10-10 08:52:11 INF Detected NAT services (count=1 log.pkg=nat)
2025-10-10 08:52:42 INF New external port opened (protocol=UDP external="[21.104.45.153:43818]" local=0.0.0.0:22000 gateway=9137a101-8ccf-4d5b-8550-0386b9c0f37c/WANDevice/urn:upnp-org:serviceId:WANIPConn1/urn:schemas-upnp-org:service:WANIPConnection:1/http://192.168.100.1:5000/ctl/IPConn log.pkg=nat)
2025-10-10 08:55:03 INF Resolved external address (uri=quic://0.0.0.0:22000 address=quic://1.53.153.230:27524 via=stun.voip.aebc.com:3478 log.pkg=connections)
2025-10-10 08:56:33 INF Resolved external address (uri=quic://0.0.0.0:22000 address=quic://1.53.153.230:27968 via=stun.voip.aebc.com:3478 log.pkg=connections)
2025-10-10 08:57:35 INF Completed initial scan (folder.label="Tất cả dữ liệu Quả Cầu" folder.id=yxqea-krdlp folder.type=sendreceive log.pkg=model)
2025-10-10 09:21:43 INF Sent usage report (version=3 log.pkg=ur)

Phone log

2025-10-10 08:51:46 INF Established secure connection (device=KEIORUM connection.local=192.168.100.144:22000 connection.remote=192.168.100.192:22000 connection.type=tcp-server connection.lan=true connection.crypto=TLS1.3-TLS_AES_128_GCM_SHA256 connection.prio=10 connection.id=63CVOVUHIJOCU25JGGUGNMO0GO log.pkg=connections)
2025-10-10 08:51:46 INF New device connection (device=KEIORUM address=192.168.100.192:22000 remote.name=OokerLaptop remote.client=syncthing remote.version=v2.0.10 log.pkg=model)
2025-10-10 08:51:46 WRN Failed to exchange Hello messages (device=KEIORUM address="[2405:4802:9386:ea90:a8b6:f765:b78e:cfcf]:22000" error=EOF log.pkg=connections)
2025-10-10 08:51:52 INF Established secure connection (device=KEIORUM connection.local="[2405:4802:9386:ea90:b76c:36e:1f44:5816]:22000" connection.remote="[2405:4802:9386:ea90:a8b6:f765:b78e:cfcf]:22000" connection.type=tcp-server connection.lan=true connection.crypto=TLS1.3-TLS_AES_128_GCM_SHA256 connection.prio=10 connection.id=63CVP0L8JFL4S4FHNRH3KSPING log.pkg=connections)
2025-10-10 08:51:52 INF Additional device connection (device=KEIORUM address="[2405:4802:9386:ea90:a8b6:f765:b78e:cfcf]:22000" count=1 log.pkg=model)
2025-10-10 08:51:52 WRN Failed to exchange Hello messages (device=KEIORUM address="[fd00:db80::a8b6:f765:b78e:cfcf]:22000" error=EOF log.pkg=connections)
2025-10-10 08:51:52 WRN Failed to exchange Hello messages (device=KEIORUM address=192.168.100.192:64176 error=EOF log.pkg=connections)
2025-10-10 08:51:52 WRN Failed to exchange Hello messages (device=KEIORUM address="[fd00:db80::a8b6:f765:b78e:cfcf]:22000" error="write tcp [fd00:db80::a3f4:1957:23e1:af41]:22000->[fd00:db80::a8b6:f765:b78e:cfcf]:22000: write: connection reset by peer" log.pkg=connections)
2025-10-10 08:51:58 INF Established secure connection (device=KEIORUM connection.local="[fd00:db80::a3f4:1957:23e1:af41]:22000" connection.remote="[fd00:db80::a8b6:f765:b78e:cfcf]:22000" connection.type=tcp-server connection.lan=true connection.crypto=TLS1.3-TLS_AES_128_GCM_SHA256 connection.prio=10 connection.id=63CVP1AAVRNFG1SD1DIGE9KJRS log.pkg=connections)
2025-10-10 08:51:58 INF Additional device connection (device=KEIORUM address="[fd00:db80::a8b6:f765:b78e:cfcf]:22000" count=2 log.pkg=model)
2

It seems that when my laptop changes the wifi (i.e. I take it to the outside), then the one-way sync from the phone to it happens. Also, the wrapper Syncthing-fork says that there are 13 conflicts. One only conflict file it lists is the one I didn’t change anything. Open the web GUI it doesn’t report any conflict.

Also, the title “Stop syncing without any error” means a different thing, but I can’t edit it now. Can some mod fix it to “Syncing stopped without any error”, or any wording that fits most?

3

It works again today. Is there any hypothesis on this?

4

My hypothesis is that it’s New connections with same priority not accepted in place of old ones until long timeout expires (>5 minutes) · Issue #9337 · syncthing/syncthing · GitHub and primary/secondary connection logic causing that.

5

I really don’t understand what is discussed in the link. Where should I read to gain the background for is?

The problem happens again btw

6

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