Client Error after updating to 2.5.27

client
1

I have update client to version 2.5.27 about 2 weeks ago.

Now is the third time that the client get stuck. Trying to open the client shows the in english (translated from italian): Error. Backup currently cannot be performed.

To make client functional again, i need to reboot the PC. Killing and restarting the client using Task Manager do not solve the problem (tryed also to turn off my antivirus firewall). After restarting, the client works correctly for about 2 days, then crash again.

After crashing, trying to use the function ‘Access to backups’ from the tray icon menu, generates this error:

Error getting server URL. Unable to access files.

On the log i see:

2026-01-17 19:09:26: ERROR: Program abort (SIGABRT)
2026-01-17 19:09:26: ERROR: Fatal exception code 0 at address 0x00007FF9835DA80A
2026-01-17 19:09:27: ERROR: Fatal exception (APPLICATION CRASHED). Crash dump written to “C:\WINDOWS\TEMP\UrBackup\v2.0.0-20260117-190926-8152-9608.dmp”

no other log is present after the crash, occured at 19:09:27 local time, and the last seen on the server i the same time.

Will send the dump file via email.

My configuration is:

CLIENT:

- OS: windows 11 25H2

- Urbackup client version: 2.5.27

- File system: NTSF

SERVER

- Version: 2.5.35

- OS: docker container on Debian Linux

Note that i have another PC on the same network, equipped with Windows 11 25H2 but client version number 2.5.26. The error seems not to occur, and client runs without problems from many days.

Sorry for my poor english :slight_smile:

2

I can confirm this Behaviour. I had to backup a bunch of Windows 2025 Servers and get the same error. Switching back to 2.5.26 fixes the problem. Running 2.5.27 on a Windows Server 2022 works like a charm, 2025 does not.

3

Now i have downgrade client to 2.5.25 and seems to run correctly. I will wait for a couple of days and then i will install 2.5.26.

Note that i leaved server version to the latest one (2.5.35)

4

Windows 25H2 client 2.5.27 crashes on all updated clients from 2.5.26 on Incremental Image Backups, I guess because they take much longer than incremental file backups. My workaround for now is to modify the Urbackup Client Service recovery settings to restart the service on first, second and subsequent failures i.e. changed from default “take no action”. Looking through the client changelog, “Properly detect Windows 11 to switch over to using a thread to prevent sleep” is likely the cause of this crashing disaster as 2.5.26 had no such issue. I’d roll back to 2.5.26 until this is fixed but it seems that my usual Winget update -r is going to pull and install 2.5.27 again ….

Source
UrBackupClientBackend.exe

Summary
Stopped working

Date
‎20/‎01/‎2026 21:23

Status
Report sent

Description
Faulting Application Path: C:\Program Files\UrBackup\UrBackupClientBackend.exe

Problem signature
Problem Event Name: BEX64
Application Name: UrBackupClientBackend.exe
Application Version: 0.0.0.0
Application Timestamp: 69078dcf
Fault Module Name: ucrtbase.dll
Fault Module Version: 10.0.26100.7623
Fault Module Timestamp: 53a0792e
Exception Offset: 00000000000a4ace
Exception Code: c0000409
Exception Data: 0000000000000007
OS Version: 10.0.26200.2.0.0.256.48
Locale ID: 2057
Additional Information 1: 32fe
Additional Information 2: 32fe17a9dca610cf13c0707932eb2260
Additional Information 3: 889d
Additional Information 4: 889de70265578e7d38ef8a7da33b3a99

Extra information about the problem
Bucket ID: a44971f1c11ef36a0e73616f7d5d5d1d (2194204574932098333)

5

strangely after reverting to 2.5.25, winget upgrade does not detect a newer version.

i usually use the winget pin command to avoid that a specific application is upgraded, even using winget upgrade -r

1 Like
6

The just released 2.5.28 should fix this issue. Thanks to everyone that reported this issue and sorry for the inconvenience.

2 Likes
7

2.5.28 client on Windows still crashing …

Source
UrBackupClientBackend.exe

Summary
Stopped working

Date
‎24/‎01/‎2026 01:57

Status
Report sent

Description
Faulting Application Path: C:\Program Files\UrBackup\UrBackupClientBackend.exe

Problem signature
Problem Event Name: APPCRASH
Application Name: UrBackupClientBackend.exe
Application Version: 0.0.0.0
Application Timestamp: 69078dcf
Fault Module Name: KERNELBASE.dll
Fault Module Version: 10.0.26100.7623
Fault Module Timestamp: 45ad608f
Exception Code: 00000000
Exception Offset: 00000000000ca80a
OS Version: 10.0.26200.2.0.0.256.48
Locale ID: 2057
Additional Information 1: e339
Additional Information 2: e339d5b583b53d446797cc825214d0f3
Additional Information 3: 9f46
Additional Information 4: 9f466a2982a88417fbd15eb2e421f759

Extra information about the problem
Bucket ID: 27f259224ce490a326f2c9552ff2b2b7 (1653605380912231095)

8

Had 2.5.28 crash on me too. Even after the 2 restart attempts i’ve configured in the service it didn’t restart until I did it manually.

9

Please send me the crash dumps.

10 
Ignore this post; it was a misunderstanding, or rather a mistake on my part.

short info about 2.5.28 cbt is also not working, maybe same. Also the Client show 2.5.38.

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image943×260 48.1 KB

11

Hi all,

After updating to 2.5.28, in 10 days i had no issues.

As the new bugs reported are related to 2.5.28 and not to 2.5.27, it’s better to open a new thread i think.

12

There is no 2.5.28 yet. Good you included the screenshot. It shows a ten year old version.

13

thanks and sorry, I have only seen the 8. I don’t know how it switched to the archive.

14

Here’s today’s log and the last dump file.

15

Timestamp in miniump shows urbackup.dll 11.01.2026 20:19 so you are likely using 2.5.27.

16

Hmm weird, the installer must have somehow failed to update it then, the client says the right version, I’ll re-run the installer manually… once it finishes downloading at 20kB/s for some reason

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image406×258 10.9 KB

image
image351×298 6.17 KB

17

Manual reinstall did update the DLL.

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image330×282 6.02 KB

1 Like