// guides/lambda-dotnet-8-deprecation

Lambda .NET 8 deprecation: Nov 10, 2026

AWS Lambda deprecates the dotnet8 runtime on Nov 10, 2026, the same day as the container-only .NET 9 runtime. Functions keep running, but AWS may stop patching them, and creating new dotnet8 functions is blocked from Jul 29, 2027 and updating them from Aug 31, 2027.

Last checked against AWS documentation: Oct 24, 2026

Key dates

Runtime	OS	Deprecation	Block function create	Block function update
.NET 8 (`dotnet8`)	Amazon Linux 2023	Nov 10, 2026	Jul 29, 2027	Aug 31, 2027
.NET 9 (`dotnet9`, container only)	Amazon Linux 2023	Nov 10, 2026	Not scheduled	Not scheduled
.NET 10 (`dotnet10`)	Amazon Linux 2023	Nov 14, 2028	Dec 14, 2028	Jan 15, 2029

What happens on each date

Deprecation (Nov 10, 2026): AWS may no longer apply security or other updates, and functions are no longer eligible for technical support. You can no longer create or update dotnet8 functions in the Lambda console; the AWS CLI, AWS SAM and CloudFormation still work.
Block function create (Jul 29, 2027): new dotnet8 functions can't be created. Existing ones can still be updated through the CLI, SAM or CloudFormation.
Block function update (Aug 31, 2027): code and configuration updates to existing dotnet8 functions are blocked. You can still switch them to a supported runtime, but rolling back may be blocked.

Existing functions keep running: AWS says you can continue to invoke them indefinitely, but deprecated runtimes are provided "as-is" and may hit issues such as certificate expiry. There is no extended-support fee for Lambda.

.NET 9 is container only. For container-image functions, AWS says deprecation notifications are not available and Lambda stops updating the base image at deprecation, so rebuilding on a supported base image is up to you.

Find affected functions

AWS lists affected $LATEST versions in the Health Dashboard and the Trusted Advisor deprecated runtimes check. AWS's CLI command, run in each Region and account:

aws lambda list-functions --function-version ALL --region us-east-1 --output text \
  --query "Functions[?Runtime=='dotnet8'].FunctionArn"

Drop --function-version ALL to list only $LATEST. Container-image functions (including all .NET 9 functions) don't have a managed runtime identifier, so check the base image in your Dockerfile instead. Paste results into the checker.

Upgrading to .NET 10

dotnet10 is the newest managed .NET runtime: deprecation Nov 14, 2028, create blocked Dec 14, 2028, update blocked Jan 15, 2029.
.NET 8 and .NET 10 both run on Amazon Linux 2023, so there is no OS change in this upgrade.
Retarget your project to .NET 10, then change the runtime identifier (Runtime: dotnet10 in SAM/CloudFormation, runtime = "dotnet10" in Terraform). AWS notes that it can't guarantee backward compatibility between major versions, so the upgrade is up to you.
Container-image functions: rebuild on a .NET 10 base image and redeploy.
AWS recommends testing on the new runtime first and using function versions and aliases so you can roll back.

All Lambda dates: Lambda runtime deprecation schedule.

Sources

FAQ

When is Lambda dotnet8 deprecated?

Nov 10, 2026. Function creation is blocked Jul 29, 2027 and function updates Aug 31, 2027, per the AWS Lambda runtimes table.

Is .NET 9 on Lambda deprecated too?

Yes. The container-only .NET 9 runtime is also deprecated Nov 10, 2026. AWS lists its block-create and block-update dates as not scheduled.

Will my dotnet8 functions stop working?

No. AWS says you can continue to invoke them indefinitely, but they no longer get security updates or technical support and may break over time.

What should I upgrade to?

dotnet10, which runs on Amazon Linux 2023 like dotnet8 and is supported until Nov 14, 2028.