scp upload very unreliable

[cazfi]

Description / Steps to reproduce the issue

I'm uploading builds (about 50Mb files) from msys2 environment to a remote server with scp. Recently this has started to fail very frequently, with scp saying "ost connection" (lack of 'L' is not a typo on my side). On the same machine I have also older msys2 installation updated on 10th of August, and that still works reliably (so problem is not with the remote server, or the connection between the machines). The issue has been present at least since 2nd of Nov.

Expected behavior

scp success

Actual behavior

scp fails with "ost connection"

Verification

• I have verified that my MSYS2 is up-to-date before submitting the report (see https://www.msys2.org/docs/updating/)

Windows Version

MSYS_NT-10.0-22631

Are you willing to submit a PR?

No response

[cazfi]

The missing 'L' part is actually only that there's no newline printed before the error, and in the terminal line wrapping 'l' fits in the previous line, after the "ETA" that's printed near the right side.

[BT-BHa]

Same for me, MSYS2 scp failing where CYGWIN scp succeeds.

source :
MSYS_NT-10.0-19045

dest:
Linux (host) 5.14.0-503.21.1.el9_5.x86_64 #1 SMP PREEMPT_DYNAMIC Wed Jan 8 17:35:30 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux

on MSYS2 :

$ pacman -Q openssl
openssl 3.4.0-1

on CYGWIN
I guess openssl is 3.0.15-1

Example of a failng upload, at random progress with this debug (vvv) info :

debug2: channel 0: rcvd adjust 131072
debug2: channel 0: rcvd adjust 131072
debug3: receive packet: type 96
debug2: channel 0: rcvd eof
debug2: channel 0: output open -> drain
debug3: receive packet: type 98
debug1: client_input_channel_req: channel 0 rtype exit-status reply 0
debug3: receive packet: type 98
debug1: client_input_channel_req: channel 0 rtype [email protected] reply 0
debug2: channel 0: rcvd eow
debug2: chan_shutdown_read: channel 0: (i0 o1 sock -1 wfd 5 efd 7 [write])
debug2: channel 0: input open -> closed
debug3: receive packet: type 97
debug2: channel 0: rcvd close
debug3: channel 0: will not send data after close
debug3: channel 0: will not send data after close
debug2: channel 0: obuf empty
debug2: chan_shutdown_write: channel 0: (i3 o1 sock -1 wfd 6 efd 7 [write])
debug2: channel 0: output drain -> closed
debug2: channel 0: almost dead
debug2: channel 0: gc: notify user
debug2: channel 0: gc: user detached
debug2: channel 0: send_close2
debug2: channel 0: send close for remote id 0
debug3: send packet: type 97
debug2: channel 0: is dead
debug2: channel 0: garbage collecting
debug1: channel 0: free: client-session, nchannels 1
debug3: channel 0: status: The following connections are open:
#0 client-session (t4 [session] r0 nm0 i3/0 o3/0 e[write]/0 fd -1/-1/7 sock -1 cc -1 nc0 io 0x00/0x00)
debug3: send packet: type 1
Transferred: sent 58169312, received 23364 bytes, in 9.8 seconds
Bytes per second: sent 5919292.3, received 2377.5
debug1: Exit status 11
scp: debug3: Sent message SSH2_FXP_WRITE I:227 O:57968640 S:261120
scp: debug3: SSH2_FXP_STATUS 0
scp: debug3: In write loop, ack for 163 261120 bytes at 41256960
lost connection