Regression in 25H2 HLK Studio (26100.8328): Create Package crashes when adding driver folder, works in previous build 26100.7705

Question

Regression in 25H2 HLK Studio (26100.8328): Create Package crashes when adding driver folder, works in previous build 26100.7705

StevenS 20

Hi Microsoft team,

We encountered a reproducible issue in the Windows 11 25H2 HLK environment after updating the HLK server from build 26100.7705 to 26100.8328.

Environment:

HLK Server OS: Windows Server 2019 Standard
HLK Controller Version: 10.1.26100.8328
HLK Studio Version: 10.0.26100.8328
Previously working: HLK build 26100.7705
Issue introduced: HLK build 26100.8328 (no OS change — only HLK server was updated)
Test client OS: Windows 11 25H2

User's image

Issue Summary:

After updating the HLK server to build 26100.8328, HLK Studio crashes during "Create Package" whenever a driver folder is added. If no driver folder is added, packaging completes successfully. This confirms the crash is specifically triggered by the "Add Driver Folder" step.

We also confirmed that packaging with a previously working driver — one that packaged successfully under build 26100.7705 — reproduces the same crash under 26100.8328.

Steps to Reproduce:

Run HLK tests successfully in the 25H2 environment (build 26100.8328)
Open the Package tab in HLK Studio
Click Add Driver Folder and select a driver package
Click Create Package → HLK Studio crashes with the exception below

Observed Behavior:

HLK tests complete successfully
DVL / CodeQL checks pass
Crash occurs regardless of signing option (including "Do not sign")
Creating a brand-new HLK project does not resolve the issue
Packaging without adding a driver folder succeeds
Packaging with a driver folder (including previously working drivers) always crashes

Exception Stack Trace:

System.InvalidOperationException: Token StartAttribute in state Element Content

would result in an invalid XML document.

at System.Xml.XmlWellFormedWriter.ThrowInvalidStateTransition(...)

at System.Xml.XmlWellFormedWriter.AdvanceState(...)

at System.Xml.XmlWellFormedWriter.WriteStartAttribute(...)

at Microsoft.Windows.Kits.Hardware.ObjectModel.Submission.PackageInfo.WritePackageInfoFile(...)

at Microsoft.Windows.Kits.Hardware.ObjectModel.Submission.PackageWriter.SavePackage(...)

at Microsoft.Windows.Kits.Hardware.ObjectModel.Submission.PackageWriter.Save(...)

at Microsoft.Windows.Kits.Hardware.UI.Views.PackageView.CreateSubmissionPackage(...)

at Microsoft.Windows.Kits.Hardware.UI.Views.PackageView.CreatePackage(...)

(Truncated for brevity — full stack trace and event log available upon request.)

Additional Log Entries (from HLK Event Log):

Failure closing INF file '[DriverA].inf' with error code: 0
Failure closing INF file '[DriverB].inf' with error code: 0
Package write attempted using SQLite Packager format version 5.0.0.0

Questions:

Is this a known issue in HLK 25H2 build 26100.8328?
Is there a hotfix or updated HLK server build that addresses this "WritePackageInfoFile" crash?

Thank you for your assistance.

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1 answer

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Answer 1

Taki Ly (WICLOUD CORPORATION) 4,440 Microsoft External Staff Moderator

Hello @StevenS ,

Thank you for sharing the detailed report and the stack trace regarding the HLK Studio crash during the "Create Package" process.

The exception System.InvalidOperationException: Token StartAttribute in state Element Content typically relates to XML formatting. In this context, it suggests that there might be an unexpected behavior occurring when WritePackageInfoFile attempts to process the package data after a driver folder is added.

At this time, it does not appear that there are widely published Known Issues focusing on this specific crash for the HLK 26100.8328 release. To help isolate the potential cause, I would recommend considering the following steps:

1. Potential mitigation for your workflow: Since this is currently blocking your validation process, you might want to consider temporarily rolling back your HLK environment (both Server and Client) to build 26100.7705, as you noted that the driver packaged successfully in that version.

2. Further isolation on Build 8328: If you have the opportunity to test further on the newer build, I suggest reviewing the driver folder setup. Sometimes, unexpected file types (like extraneous .pdb or hidden files) or long directory paths might trigger edge-case behaviors. You might try moving the driver package to a simplified, short path (e.g., C:\TestDriver\) to see if the crash still occurs.

Additionally, exporting the full logs from Windows Event Viewer -> Applications and Services Logs -> HLK might provide more clues about the state of the application right before it closes.

3. Engaging Official Support: If the issue is consistently reproducible regardless of the folder setup, it may be beneficial to reach out to the official support team so they can investigate this on a deeper level. I suggest submitting a support request through this channel: Windows developer support - Contact Us

Providing them with the full stack trace, the Event Logs, and any dump files might assist the engineers in reproducing the behavior and checking if a hotfix could be necessary.

Hope these information help! If you found my response helpful or informative, I would greatly appreciate it if you could follow this guide for your confirmation.

Thank you.

Daniel Mitchell 10 Reputation points

2026-06-05T02:38:21.5733333+00:00

I'm seeing exactly the same thing using the VHLK (which is currently HLK 26100.8328) -- same error logs, same "fails if I include the driver, passes if I don't".
Taki Ly (WICLOUD CORPORATION) 4,440 Reputation points Microsoft External Staff Moderator

2026-06-05T04:26:47.7333333+00:00

Hi @Daniel Mitchell ,

Thank you for sharing your experience. It is very helpful context to know that similar behavior is occurring on the VHLK (Virtual HLK).

Seeing this WritePackageInfoFile exception on the pre-configured VHLK environment suggests that the symptom might not be tied to a specific local configuration and could potentially relate to how this specific build handles package data when a driver folder is present.

If this is currently stopping your submission process, you might want to consider utilizing a previous VHLK image (such as build 26100.7705) or returning to an older VM checkpoint, if you have one available, to keep your workflow moving.

To assist the engineering team in investigating this behavior further, I would suggest submitting a direct support request through the dedicated business portal:

Support for Business - Create Ticket

When describing the issue in your ticket, mentioning that it reproduces natively on the VHLK could be beneficial for the support engineers as they look into this.

Please feel free to share any updates or insights you might receive, as it would be very helpful for others in the community facing the same scenario.Thank you.
Taki Ly (WICLOUD CORPORATION) 4,440 Reputation points Microsoft External Staff Moderator

2026-06-05T04:27:43.6233333+00:00

Hi @StevenS ,

Just checking in, do you have any update?
Daniel Mitchell 10 Reputation points

2026-06-08T18:22:22.29+00:00

Where can I find older VHLK versions? The links from https://www.microsoft.com/en-us/evalcenter/evaluate-virtual-hardware-lab-kit all take me to the latest version. (similarly, https://learn.microsoft.com/en-us/windows-hardware/test/hlk/ takes me to an HLKSetup.exe that downloads the latest version of the HLK)
Daniel Mitchell 10 Reputation points

2026-06-08T20:15:29.22+00:00

Possibly related; I'm getting the "Driver package not specified" error as in
https://learn.microsoft.com/en-us/answers/questions/5781956/(hlk)-driver-attribute-test-fails-with-driver-pack
even though I've specified the driver folder in the Package tab, and it's the same contents on the (V)HLK Studio machine as what's installed on the test machine and I've re-created the project, re-selected the driver, etc as per https://community.osr.com/t/hlk-apivalidator-queryvalidatedriverfolder-missing/59336

(and also "Runtime parameter QueryDriverFilePath is a zero-length string" on RequiredDriverAttributesTests::ValidateRequiredDriverAttributes, which also feels potentially related to "adding driver files doesn't work")
Taki Ly (WICLOUD CORPORATION) 4,440 Reputation points Microsoft External Staff Moderator

2026-06-09T04:51:55.73+00:00

Hi @Daniel Mitchell ,

Thanks for the additional details.

Regarding older VHLK versions: Microsoft typically only hosts the newest release publicly. Without local backups or a Visual Studio Subscription, finding a public download link can be difficult. I suggest asking the support team directly in your ticket if they can provide a secure download link for build 26100.7705 to help unblock you.

Regarding your observation about the "Driver package not specified" and "zero-length string" errors. It is possible these test failures share a root cause with the packaging crash. If the system is struggling to parse the driver folder path, it could explain why both test validation and XML packaging behave unexpectedly. I recommend appending these test failure details and API logs to your support request. This might give the engineering team valuable clues regarding how the driver folder handling is impacting the build.

Please let us know if support provides a workaround or an older build link. If you have any further questions, feel free to post a new thread in the forum and I'll be happy to assist you.

Thank you.
Taki Ly (WICLOUD CORPORATION) 4,440 Reputation points Microsoft External Staff Moderator

2026-06-09T04:52:41.86+00:00

Hi @StevenS ,

As we haven’t heard back from you for a while, we’ll go ahead and close this thread for now. If you still need assistance later, feel free to reach out.

Thank you for your understanding.
StevenS 20 Reputation points

2026-06-09T07:34:19.1733333+00:00

Hi @Taki Ly (WICLOUD CORPORATION)

Thank you for following up.

The issue is still unresolved on our side. We reviewed the suggested Engage Center / Hardware Submission & Signing support path, but currently we do not have access to a Partner Center Hardware Developer Program account that can create this type of support case.

The issue remains reproducible on HLK 25H2 build 26100.8328 during Package tab → Add Driver Folder → Create Package. It also reproduces with “Do not sign”, a newly created HLK project, and a single driver package. The stack trace still points to PackageInfo.WritePackageInfoFile / PackageWriter.SavePackage.

Also, another user has reported the same behavior on VHLK 26100.8328, where packaging fails when a driver folder is included and succeeds when no driver is included.

We would like to provide the current status for the record.

Thank you.
Taki Ly (WICLOUD CORPORATION) 4,440 Reputation points Microsoft External Staff Moderator

2026-06-09T10:03:13.45+00:00

Hi @StevenS ,

Thanks for documenting the current status for the record. It is certainly very helpful for the rest of the community tracking this issue.

Out of curiosity, is there a specific blocker preventing your team from accessing the Partner Center? If you are an employee, it might just be a matter of having your IT administrator assign the "Support Contributor" role to your account.

However, if your organization simply hasn't registered for the program yet, you might want to consider creating a Hardware Developer account. To set one up, your company would generally need an Entra ID (Azure AD) tenant and an Extended Validation (EV) Code Signing Certificate. If you are interested in exploring this path, I recommend checking the official registration guide here: Register for the Hardware Program

Thanks again for keeping us informed.
Daniel Mitchell 10 Reputation points

2026-06-25T16:16:15.2733333+00:00
For what it's worth, we do have the right sort of account, so have a ticket open for this and I've been sending over crash logs etc. The most recent response was:

The internal PG team has conducted a thorough investigation and has been able to reproduce the issue. They are currently collaborating with the HLK team to implement a fix. In the meantime, to help unblock you, please refer to the following documentation:

Working with extension INF files in the Windows Hardware Dashboard - Windows drivers | Microsoft Learn This provides guidance for submissions involving extension drivers. By following the outlined recommendations and submitting your base driver and extension INF separately, you should be able to avoid the issue you are currently encountering.

Our driver does have an extension, and removing that from the driver package folder meant HLK Studio doesn't crash and I can successfully create a package, in case that's any help to you @StevenS .
José Simões 20 Reputation points MVP

2026-07-03T12:18:46.7066667+00:00

I'm also facing this problem.
Eivind Henriksen 0 Reputation points

2026-07-14T12:27:34.0966667+00:00
We're seeing this too, and wanted to add a different reproduction scenario that suggests the root cause is broader than extension INF files.

We reproduce the same Token StartAttribute in state Element Content / WritePackageInfoFile crash, but through the HLK .NET API rather than the Studio UI, and without any extension INF files, only base drivers, via the DUA (Driver Update Acceptable) flow.

Our reproduction path:

Open a shell DUA package (ConnectionType.UpdatePackage) with PackageManager

Call PackageWriter.AddReplacementDriver() with a base driver folder (no extension INFs)

Call PackageWriter.Save() -> throws Token StartAttribute in state Element Content from PackageInfo.WritePackageInfoFile

Additional API-level detail: AddReplacementDriver returns has_error=True with completely empty errors and warnings StringCollection out-parameters, no diagnostic message is surfaced to the caller. Calling Save() without any prior AddReplacementDriver succeeds normally, confirming that AddReplacementDriver corrupts the writer's internal state.

Workaround confirmed: Rolling back from 26100.8328 to 26100.4946 resolves the issue completely for our scenario.
José Simões 20 Reputation points MVP

2026-08-31T15:29:35.08+00:00

Any update on this please? Is there an expected release date for a fix? Thanks.