CS1705 Errors After Upgrading to .NET 9 Syncfusion Assemblies Referencing Unexpected Versions (29.2462.11.0, 30.1462.39.0)

[Sander Zwaenepoel]

I'm encountering an issue after upgrading my application from .NET Framework to .NET 9. During build, I get the following errors:

Severity Code Project Description File Line Suppression State Details

Error (active) CS1705 Isolvit.Project.Wpf Assembly 'Isolvit.Framework.Reporting' with identity 'Isolvit.Framework.Reporting, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' uses 'Syncfusion.DocIO.Base, Version=30.1462.39.0, Culture=neutral, PublicKeyToken=3d67ed1f87d44c89' which has a higher version than referenced assembly 'Syncfusion.DocIO.Base' with identity 'Syncfusion.DocIO.Base, Version=30.1.39.0, Culture=neutral, PublicKeyToken=3d67ed1f87d44c89' D:\isolvit\Elektrokontakt.Turritopsis2022\Application\Isolvit.Project.Wpf\CSC 1

I’m confused about why the version number includes “462” in the middle (30.1462.39.0, 29.2462.11.0), since I was expecting 30.1.39, 29.2.11.0. I already tried downgrading back to the original versions I was using, but the issue persists.

Attachment: errors_1a5d7456.png

[Suresh Ganesan]

Hi Sander,
Regarding: I'm encountering an issue after upgrading my application from .NET Framework to .NET 9. During build, I get the following errors
We have tried to reproduce the reported issue in the WPF sample using .NET 9.0 and version v30.1.39, but it is working properly on our end. We have attached the sample along with the output document for your reference.
Upon further analysis, we suspect that the issue may be due to a NuGet package version mismatch on your end. To resolve this issue, kindly follow the below steps:
1. Ensure All Syncfusion Packages Are Updated
    Use NuGet Package Manager to update latest version v30.1.39:
     1. Syncfusion.DocIO. wpf
     2. Syncfusion.DocToPdfConverter.wpf
     3. Syncfusion.Pdf. WPF
     4. Any other related Syncfusion libraries
2. Clean and rebuild
     1. Delete bin and obj folders.
     2. Rebuild the solution.
Kindly refer to the below documentation for your reference.
How to clear NuGet cache?

If you are still facing the issue, kindly share the below details. This will allow us to analyze the problem and provide you with a suitable solution at the earliest.
1. Input document.
2. Issue reproducible sample.
3. Environment details (Operating System, if using cloud service, share cloud service and plan details).

Regarding: I’m confused about why the version number includes “462” in the middle
The versions of v30.1.39 and v29.2.11 refer to NuGet package releases. Each NuGet package contains multiple assemblies targeting different framework versions. In this context, the number “462” within the version (e.g., 30.1462.39.0) indicates the target framework version internally. Assemblies targeting frameworks such as .NET Framework 4.6.2 appear with this identifier. 

Regards,
Suresh Ganesan

Attachment: ConvertWordtoPDF_d1aa1dda.zip

[Sprunki Retake]

I ran into the exact same issue after moving to .NET 9—turned out Syncfusion changed their versioning format, and the "1462" is actually tied to the build or release date, not a semantic version bump. Matching exact assembly versions across all projects fixed it for me (nuget restore sometimes grabbed mismatched ones). Took less time to sort out than a Sprunki Retake S-rank—just needed the right rhythm!

Hỏi ChatGPT

[Chrispine Agunja Imbo]

Hi Sprunki,

We are glad. Please let us know if you need further assistance.

Regards,

Chris

[Brett Cavanaugh]

This looks like a classic version mismatch issue after upgrading. Ensuring all Syncfusion packages are aligned and cleaning the build usually helps resolve these CS1705 errors

[Alice Awour Jagongo]

Hi Brett,

We're glad that your issue has been resolved. We will proceed to close this but please, feel free to reach out if you have any further queries.

Regards,

Alice.