Azure Functions
An Azure service that provides an event-driven serverless compute platform.
Azure Communication Services "System.Memory, Version=4.0.1.2" file not found exception
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Farhat Abbas
0
Reputation points
Azure communication services work fine on a console application but if I write this code on a function app it throws error "FileNotFoundException: Could not load file or assembly 'System.Memory, Version=4.0.1.2, Culture=neutral, PublicKeyToken=xxxxxxx' or one of its dependencies. The system cannot find the file specified."
After adding assembly reference for "Azure.Communication.Email" it update the latest version of System.Memory and doesn't give option to downgrade it.
Azure Functions
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Pravallika KV 2,690 Reputation points Microsoft External Staff Moderator2025-12-03T19:50:41.4066667+00:00 Hi @Farhat Abbas ,
Thanks for reaching out to Microsoft Q&A.
Could you please provide your function code and .csproj file?
- Make sure that your function app's
.csprojfile is targeting a compatible framework version. For example, if you are using Azure Functions v4, ensure you have something like:
<PropertyGroup> <TargetFramework>net8.0</TargetFramework> <AzureFunctionsVersion>v4</AzureFunctionsVersion> </PropertyGroup>- If adding the assembly reference for
Azure.Communication.EmailupdatedSystem.Memoryto a version that causes issues, you may need to manually add a reference to the specific version ofSystem.Memoryyou want:
<PackageReference Include="System.Memory" Version="4.5.0" />- _FunctionsSkipCleanOutput: Sometimes, the Azure Functions environment doesn't copy all required files. To prevent cleaning the output, you can add:
<_FunctionsSkipCleanOutput>true</_FunctionsSkipCleanOutput>- If
System.Memoryis updated automatically and you don't need the latest version for your application, you might consider removing it from your.csprojand adding it back explicitly with the desired version. - Ensure that your function app in Azure has the correct application settings and dependencies configured. Sometimes issues can arise from misconfigured settings or missing references.
- Make sure that your function app's
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Pravallika KV 2,690 Reputation points Microsoft External Staff Moderator
2025-12-04T19:23:31.69+00:00 Hi @Farhat Abbas , following up to see if you had a chance to check the above response and if it was helpful. Please do let me know if you have any further queries.
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