aws-rds: serverlessV2 auto-pause feature is not supported by aurora-mysql 8.4.mysql_aurora.8.4.7

[AdrianDev374]

Describe the bug

I'm upgrading to Aurora MySQL version 8.4. I'm coming from version 3.12.

I decided to upgrade manually for testing purposes. I updated the user passwords, did everything, and the application is working correctly.

When updating the AWS CDK code (to prevent drift), I encountered the following error:

Regression Issue

• Select this option if this issue appears to be a regression.

Last Known Working CDK Library Version

No response

Expected Behavior

It should support this feature since it's the latest version, and yesterday they announced improvements even beyond the potential of version 4 of the platform.

Current Behavior

Same error description

Reproduction Steps

Simply the basic use of deploying a serverlessv2 database with the latest version of Aurora 8.4

Possible Solution

No response

Additional Information/Context

No response

AWS CDK Library version (aws-cdk-lib)

2.260.0

AWS CDK CLI version

2.1129.0

Node.js Version

24.19

OS

Linux

Language

TypeScript

Language Version

6.0.3

Other information

No response

[pahud]

Hi @AdrianDev374,

┌────────────────────────────────────────────────────────────────┐
│ 🔴 Reported State                                              │
│ Synth fails: "serverlessV2 auto-pause feature is not           │
│ supported by aurora-mysql 8.4.mysql_aurora.8.4.7"              │
└───────────────────────────────┬────────────────────────────────┘
                                │
                                ▼
┌────────────────────────────────────────────────────────────────┐
│ 🔍 Root Cause                                                  │
│ AuroraMysqlEngineVersion.of() without a major-version arg      │
│ can't detect 8.4 → auto-pause support flag stays false         │
│ (aws-rds/lib/cluster-engine.ts, of())                          │
└───────────────────────────────┬────────────────────────────────┘
                                │
                                ▼
┌────────────────────────────────────────────────────────────────┐
│ 🟢 Suggested Fix                                               │
│ Workaround: .of('8.4.mysql_aurora.8.4.7', '8.4')               │
│ Real fix: infer major from full version — PR #38516            │
└────────────────────────────────────────────────────────────────┘

Thanks for the report — this is a good catch, and the good news is there is a one-line workaround.

I was able to reproduce this locally on aws-cdk-lib 2.260.0. Aurora MySQL 8.4 absolutely does support Serverless v2 auto-pause; the problem is how the engine version gets constructed. Since there is no built-in constant for 8.4 yet, I assume you are using AuroraMysqlEngineVersion.of() — and when the second (major version) argument is omitted, CDK cannot tell this is an 8.4 engine, so the auto-pause support flag defaults to false:

aws-cdk/packages/aws-cdk-lib/aws-rds/lib/cluster-engine.ts

Lines 744 to 747 in 48fb66e

	const coercedVersion = semver.valid(semver.coerce(auroraMysqlMajorVersion));
	const serverlessV2AutoPauseSupported = auroraMysqlMajorVersion === '8.0'
	? auroraMysqlFullVersion >= '8.0.mysql_aurora.3.08.0'
	: (coercedVersion != null && semver.satisfies(coercedVersion, '>=8.1'));

That flag then trips the validation in DatabaseCluster:

aws-cdk/packages/aws-cdk-lib/aws-rds/lib/cluster.ts

Lines 1228 to 1231 in 48fb66e

	if (this.serverlessV2AutoPauseDuration) {
	if (!config.features?.serverlessV2AutoPauseSupported) {
	throw new ValidationError(lit`ServerlessV2AutoPauseNotSupported`, `serverlessV2 auto-pause feature is not supported by ${this.engine?.engineType} ${this.engine?.engineVersion?.fullVersion}.`, this);
	}

Workaround (verified working on 2.260.0): pass the major version explicitly:

version: rds.AuroraMysqlEngineVersion.of('8.4.mysql_aurora.8.4.7', '8.4')

Could you confirm your code was calling .of() without the second argument? If you are constructing the version some other way, please share the engine snippet so we can double-check.

There is already an open fix, PR #38516, which infers the major version from the full version string so the explicit argument will not be needed, and #37924 / PR #37992 track adding built-in VER_8_4_x constants. Contributions and reviews on those are very welcome!

[AdrianDev374]

Hi @pahud

Yes, it is indeed using the "of" method. Analyzing the package, I realized that adding the second parameter would work. That's why I decided to open the pull request #38516 with those improvements. But I don't know if I should do anything else in the PR