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Server Error after build the customisation project in 2025 R2.

  • October 13, 2025
  • 7 replies
  • 168 views
A
Freshman I

Could not load file or assembly 'Microsoft.Extensions.Options.ConfigurationExtensions' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.IO.FileLoadException: Could not load file or assembly 'Microsoft.Extensions.Options.ConfigurationExtensions' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
How can I resolve this issue? Thanks in advance for your help!

Best answer by praveenpo

Hi ​@aswathyk17 ,

Add the Microsoft.Extensions.Options.ConfigurationExtensions dll from bin folder of the to your extension project will resolve the issue.

7 replies

praveenpo
Semi-Pro III
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  • praveenpo
  • Semi-Pro III
  • Answer
  • October 13, 2025

Hi ​@aswathyk17 ,

Add the Microsoft.Extensions.Options.ConfigurationExtensions dll from bin folder of the to your extension project will resolve the issue.

Praveen
Chris Hackett
mohammadnawaz51
A
Captain II
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  • aiwan
  • Captain II
  • October 13, 2025

Hi ​@aswathyk17 

 

You should first map the compile folder in your .csproj file to the \bin folder of the customisation.

Then copy the contents of your Acumatica install root \bin folder into the \bin folder of your instance.

Then you should add a target to your csproj file like this:

<Target Name="CopyDLL" AfterTargets="Build"> <Copy SourceFiles="$(OutputPath)$(AssemblyName).dll" DestinationFolder="$(AcumaticaSiteDir)Bin" SkipUnchangedFiles="False" /> </Target>

Aleks
Chris Hackett
DipakNilkanth
Pro III
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Hi ​@aswathyk17,

You can use the attached DLL file, which should resolve your issue. After that, as suggested by ​@praveenpo , please add a reference to this file in your extension project.

1 Attachments
Dipak Nilkanth || MVP @2025 || https://www.linkedin.com/in/dipak-nilkanth-293591102 || Acumatica Developer
Chris Hackett
A
Freshman I
  • aswathyk17
  • Author
  • Freshman I
  • October 13, 2025

I have added Microsoft.Extensions.Options.ConfigurationExtensions dll from bin folder  to the extension project(added as reference) and then build the project. But same error coming

DipakNilkanth
Pro III
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Hi ​@aswathyk17,
The DLL you added has already been modified. Please copy the above attached DLL from my previous comment into your working bin folder and then refresh the Acumatica instance.

Dipak Nilkanth || MVP @2025 || https://www.linkedin.com/in/dipak-nilkanth-293591102 || Acumatica Developer
Chris Hackett
darylbowman
Captain II
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You can use the attached DLL file, which should resolve your issue.

I’m sure we’re all friends here, but downloading a DLL from the internet is a supremely awful practice.

Daryl⚡Freelance Acumatica developer (MVPx2🏆) ⏩linkedin.com/in/darylbowman 🛒store.deftstrokesdev.com
Chris Hackett
A
Captain II
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  • aiwan
  • Captain II
  • October 14, 2025

I have added Microsoft.Extensions.Options.ConfigurationExtensions dll from bin folder  to the extension project(added as reference) and then build the project. But same error coming

The way I presented is the way to fix this and stop it from recurring.

 

You will be in DLL hell if you keep downloading and replacing errored ones.

Aleks
Chris Hackett
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