SqlDatabase: Error: JSON: expected value at line 1 column 1

[ognif]

Problem description

SqlServerDsc/SqlDatabase return a nothing to say error: expected value at line 1 column 1
I tried with different properties, with and without "Credentials".
After revert to SqlServerDsc-17.3.0 it works without any issue.

Verbose logs

{"timestamp":"2026-01-09T12:46:18.950095Z","level":"TRACE","fields":{"message":"Current working directory: C:\\\\Program Files\\\\DSC"},"target":"dsc_lib::dscresources::command_resource","line_number":772}
{"timestamp":"2026-01-09T12:46:18.958694Z","level":"TRACE","fields":{"message":"Writing to command STDIN: {\"resources\":[{\"name\":\"SqlServerDsc/SqlDatabase\",\"type\":\"SqlServerDsc/SqlDatabase\",\"properties\":{\"ServerName\":\"V-MSSQL176.xxx\",\"InstanceName\":\"MSSQLSERVER\",\"Name\":\"model\",\"RecoveryModel\":\"Simple\",\"Ensure\":\"Present\",\"Credential\":{\"userName\":\"xxx\",\"password\":\"xxx\"}}}],\"metadata\":{\"Microsoft.DSC\":{\"context\":\"configuration\"}}}"},"target":"dsc_lib::dscresources::command_resource","line_number":666}
{"timestamp":"2026-01-09T12:46:19.483147Z","level":"DEBUG","fields":{"message":"PID 7336: PSVersion=7.5.3"},"target":"dsc_lib::dscresources::command_resource","line_number":986}
{"timestamp":"2026-01-09T12:46:19.483924Z","level":"DEBUG","fields":{"message":"PID 7336: PSPath=C:\\Program Files\\PowerShell\\7"},"target":"dsc_lib::dscresources::command_resource","line_number":986}
{"timestamp":"2026-01-09T12:46:19.484624Z","level":"DEBUG","fields":{"message":"PID 7336: PSModulePath=C:\\Users\\S954622\\Documents\\PowerShell\\Modules;C:\\Program Files\\PowerShell\\Modules;c:\\program files\\powershell\\7\\Modules;C:\\Program Files\\WindowsPowerShell\\Modules;C:\\WINDOWS\\system32\\WindowsPowerShell\\v1.0\\Modules;C:\\Program Files (x86)\\Microsoft SQL Server\\160\\Tools\\PowerShell\\Modules\\"},"target":"dsc_lib::dscresources::command_resource","line_number":986}
{"timestamp":"2026-01-09T12:46:19.575990Z","level":"DEBUG","fields":{"message":"Process 'pwsh' id 7336 exited with code 0"},"target":"dsc_lib::dscresources::command_resource","line_number":710}
{"timestamp":"2026-01-09T12:46:19.577057Z","level":"DEBUG","fields":{"message":"Parsing input as stdin"},"target":"dsc_lib::dscresources::command_resource","line_number":842}
{"timestamp":"2026-01-09T12:46:19.577105Z","level":"INFO","fields":{"message":"Getting current state for set by invoking get on 'Microsoft.DSC/PowerShell' using 'pwsh'"},"target":"dsc_lib::dscresources::command_resource","line_number":150}
{"timestamp":"2026-01-09T12:46:19.578180Z","level":"TRACE","fields":{"message":"Invoking command 'pwsh' with args Some([\"-NoLogo\", \"-NonInteractive\", \"-NoProfile\", \"-ExecutionPolicy\", \"Bypass\", \"-Command\", \"$Input | ./psDscAdapter/powershell.resource.ps1 Get\"])"},"target":"dsc_lib::dscresources::command_resource","line_number":770}
{"timestamp":"2026-01-09T12:46:19.578302Z","level":"TRACE","fields":{"message":"Current working directory: C:\\\\Program Files\\\\DSC"},"target":"dsc_lib::dscresources::command_resource","line_number":772}
{"timestamp":"2026-01-09T12:46:19.587060Z","level":"TRACE","fields":{"message":"Writing to command STDIN: {\"resources\":[{\"name\":\"SqlServerDsc/SqlDatabase\",\"type\":\"SqlServerDsc/SqlDatabase\",\"properties\":{\"ServerName\":\"V-MSSQL176.xxx\",\"InstanceName\":\"MSSQLSERVER\",\"Name\":\"model\",\"RecoveryModel\":\"Simple\",\"Ensure\":\"Present\",\"Credential\":{\"userName\":\"xxx\",\"password\":\"xxx\"}}}],\"metadata\":{\"Microsoft.DSC\":{\"context\":\"configuration\"}}}"},"target":"dsc_lib::dscresources::command_resource","line_number":666}
{"timestamp":"2026-01-09T12:46:20.102526Z","level":"DEBUG","fields":{"message":"PID 224: PSVersion=7.5.3"},"target":"dsc_lib::dscresources::command_resource","line_number":986}
{"timestamp":"2026-01-09T12:46:20.103210Z","level":"DEBUG","fields":{"message":"PID 224: PSPath=C:\\Program Files\\PowerShell\\7"},"target":"dsc_lib::dscresources::command_resource","line_number":986}
{"timestamp":"2026-01-09T12:46:20.103873Z","level":"DEBUG","fields":{"message":"PID 224: PSModulePath=C:\\Users\\S954622\\Documents\\PowerShell\\Modules;C:\\Program Files\\PowerShell\\Modules;c:\\program files\\powershell\\7\\Modules;C:\\Program Files\\WindowsPowerShell\\Modules;C:\\WINDOWS\\system32\\WindowsPowerShell\\v1.0\\Modules;C:\\Program Files (x86)\\Microsoft SQL Server\\160\\Tools\\PowerShell\\Modules\\"},"target":"dsc_lib::dscresources::command_resource","line_number":986}
{"timestamp":"2026-01-09T12:46:20.106442Z","level":"DEBUG","fields":{"message":"PID 224: jsonInput={\"resources\":[{\"name\":\"SqlServerDsc/SqlDatabase\",\"type\":\"SqlServerDsc/SqlDatabase\",\"properties\":{\"ServerName\":\"V-MSSQL176.xxx\",\"InstanceName\":\"MSSQLSERVER\",\"Name\":\"model\",\"RecoveryModel\":\"Simple\",\"Ensure\":\"Present\",\"Credential\":{\"userName\":\"xxx\",\"password\":\"xxx\"}}}],\"metadata\":{\"Microsoft.DSC\":{\"context\":\"configuration\"}}}"},"target":"dsc_lib::dscresources::command_resource","line_number":986}
{"timestamp":"2026-01-09T12:46:20.251091Z","level":"DEBUG","fields":{"message":"PID 224: Reading from Get-DscResource cache file C:\\Users\\S954622\\AppData\\Local\\dsc\\PSAdapterCache.json"},"target":"dsc_lib::dscresources::command_resource","line_number":986}
{"timestamp":"2026-01-09T12:46:20.265883Z","level":"DEBUG","fields":{"message":"PID 224: Checking cache for stale entries"},"target":"dsc_lib::dscresources::command_resource","line_number":986}
{"timestamp":"2026-01-09T12:46:21.496029Z","level":"DEBUG","fields":{"message":"PID 224: Checking cache for stale PSModulePath"},"target":"dsc_lib::dscresources::command_resource","line_number":986}
{"timestamp":"2026-01-09T12:46:21.587766Z","level":"DEBUG","fields":{"message":"PID 224: PSModulePath diff ''"},"target":"dsc_lib::dscresources::command_resource","line_number":986}
{"timestamp":"2026-01-09T12:46:21.608618Z","level":"DEBUG","fields":{"message":"PID 224: OS version: Microsoft Windows NT 10.0.26100.0"},"target":"dsc_lib::dscresources::command_resource","line_number":986}
{"timestamp":"2026-01-09T12:46:21.608937Z","level":"DEBUG","fields":{"message":"PID 224: PowerShell version: 7.5.3"},"target":"dsc_lib::dscresources::command_resource","line_number":986}
{"timestamp":"2026-01-09T12:46:22.767496Z","level":"TRACE","fields":{"message":"PID 224: [\r\n  \"InstanceName\",\r\n  \"ServerName\",\r\n  \"Credential\",\r\n  \"Protocol\",\r\n  \"Port\",\r\n  \"Reasons\",\r\n  \"Name\",\r\n  \"Ensure\",\r\n  \"Collation\",\r\n  \"CompatibilityLevel\",\r\n  \"RecoveryModel\",\r\n  \"OwnerName\",\r\n  \"SnapshotIsolation\",\r\n  \"CatalogCollation\",\r\n  \"IsLedger\",\r\n  \"AcceleratedRecoveryEnabled\",\r\n  \"AnsiNullDefault\",\r\n  \"AnsiNullsEnabled\",\r\n  \"AnsiPaddingEnabled\",\r\n  \"AnsiWarningsEnabled\",\r\n  \"ArithmeticAbortEnabled\",\r\n  \"AutoClose\",\r\n  \"AutoCreateIncrementalStatisticsEnabled\",\r\n  \"AutoCreateStatisticsEnabled\",\r\n  \"AutoShrink\",\r\n  \"AutoUpdateStatisticsAsync\",\r\n  \"AutoUpdateStatisticsEnabled\",\r\n  \"BrokerEnabled\",\r\n  \"ChangeTrackingAutoCleanUp\",\r\n  \"ChangeTrackingEnabled\",\r\n  \"CloseCursorsOnCommitEnabled\",\r\n  \"ConcatenateNullYieldsNull\",\r\n  \"DatabaseOwnershipChaining\",\r\n  \"DataRetentionEnabled\",\r\n  \"DateCorrelationOptimization\",\r\n  \"EncryptionEnabled\",\r\n  \"HonorBrokerPriority\",\r\n  \"IsFullTextEnabled\",\r\n  \"IsParameterizationForced\",\r\n  \"IsReadCommittedSnapshotOn\",\r\n  \"IsSqlDw\",\r\n  \"IsVarDecimalStorageFormatEnabled\",\r\n  \"LocalCursorsDefault\",\r\n  \"NestedTriggersEnabled\",\r\n  \"NumericRoundAbortEnabled\",\r\n  \"QuotedIdentifiersEnabled\",\r\n  \"ReadOnly\",\r\n  \"RecursiveTriggersEnabled\",\r\n  \"RemoteDataArchiveEnabled\",\r\n  \"RemoteDataArchiveUseFederatedServiceAccount\",\r\n  \"TemporalHistoryRetentionEnabled\",\r\n  \"TransformNoiseWords\",\r\n  \"Trustworthy\",\r\n  \"ChangeTrackingRetentionPeriod\",\r\n  \"DefaultFullTextLanguage\",\r\n  \"DefaultLanguage\",\r\n  \"MaxDop\",\r\n  \"MaxDopForSecondary\",\r\n  \"MirroringRedoQueueMaxSize\",\r\n  \"MirroringTimeout\",\r\n  \"TargetRecoveryTime\",\r\n  \"TwoDigitYearCutoff\",\r\n  \"MaxSizeInBytes\",\r\n  \"FilestreamDirectoryName\",\r\n  \"MirroringPartner\",\r\n  \"MirroringPartnerInstance\",\r\n  \"MirroringWitness\",\r\n  \"PersistentVersionStoreFileGroup\",\r\n  \"PrimaryFilePath\",\r\n  \"RemoteDataArchiveCredential\",\r\n  \"RemoteDataArchiveEndpoint\",\r\n  \"RemoteDataArchiveLinkedServer\",\r\n  \"RemoteDatabaseName\",\r\n  \"ChangeTrackingRetentionPeriodUnits\",\r\n  \"ContainmentType\",\r\n  \"DelayedDurability\",\r\n  \"FilestreamNonTransactedAccess\",\r\n  \"LegacyCardinalityEstimation\",\r\n  \"LegacyCardinalityEstimationForSecondary\",\r\n  \"MirroringSafetyLevel\",\r\n  \"PageVerify\",\r\n  \"ParameterSniffing\",\r\n  \"ParameterSniffingForSecondary\",\r\n  \"QueryOptimizerHotfixes\",\r\n  \"QueryOptimizerHotfixesForSecondary\",\r\n  \"UserAccess\"\r\n]"},"target":"dsc_lib::dscresources::command_resource","line_number":988}
{"timestamp":"2026-01-09T12:46:27.244983Z","level":"TRACE","fields":{"message":"PID 224: Output: {\"name\":\"SqlServerDsc/SqlDatabase\",\"type\":\"SqlServerDsc/SqlDatabase\",\"properties\":{\"MirroringPartner\":\"\",\"OwnerName\":\"sa\",\"QueryOptimizerHotfixesForSecondary\":\"Primary\",\"MirroringTimeout\":0,\"CloseCursorsOnCommitEnabled\":false,\"ParameterSniffingForSecondary\":\"Primary\",\"RecoveryModel\":\"Simple\",\"AnsiPaddingEnabled\":false,\"ChangeTrackingAutoCleanUp\":false,\"IsSqlDw\":false,\"ReadOnly\":false,\"UserAccess\":\"Multiple\",\"RemoteDatabaseName\":\"\",\"NestedTriggersEnabled\":true,\"IsParameterizationForced\":false,\"DelayedDurability\":\"Disabled\",\"IsFullTextEnabled\":false,\"CompatibilityLevel\":\"Version160\",\"Trustworthy\":false,\"Port\":null,\"DefaultLanguage\":1033,\"AutoUpdateStatisticsAsync\":false,\"DatabaseOwnershipChaining\":false,\"MaxDop\":0,\"AutoClose\":false,\"EncryptionEnabled\":false,\"FilestreamNonTransactedAccess\":\"Off\",\"PrimaryFilePath\":\"S:\\\\MSSQL\\\\Data\\\\MSSQL16.MSSQLSERVER\\\\MSSQL\\\\DATA\",\"ChangeTrackingRetentionPeriodUnits\":\"None\",\"ChangeTrackingEnabled\":false,\"DefaultFullTextLanguage\":1033,\"Name\":\"model\",\"ConcatenateNullYieldsNull\":false,\"MirroringSafetyLevel\":\"None\",\"DataRetentionEnabled\":false,\"ServerName\":\"V-MSSQL176.xxx\",\"TargetRecoveryTime\":60,\"HonorBrokerPriority\":false,\"Reasons\":[],\"IsVarDecimalStorageFormatEnabled\":false,\"MaxDopForSecondary\":0,\"ContainmentType\":\"None\",\"QueryOptimizerHotfixes\":\"Off\",\"FilestreamDirectoryName\":\"\",\"NumericRoundAbortEnabled\":false,\"AnsiNullsEnabled\":false,\"TemporalHistoryRetentionEnabled\":null,\"MirroringPartnerInstance\":\"\",\"SnapshotIsolation\":false,\"PersistentVersionStoreFileGroup\":\"PRIMARY\",\"TwoDigitYearCutoff\":2049,\"Ensure\":\"Present\",\"AnsiNullDefault\":false,\"RemoteDataArchiveUseFederatedServiceAccount\":false,\"Collation\":\"Latin1_General_CI_AS\",\"AnsiWarningsEnabled\":false,\"AutoCreateStatisticsEnabled\":true,\"MirroringRedoQueueMaxSize\":0,\"RemoteDataArchiveEndpoint\":\"\",\"TransformNoiseWords\":false,\"MaxSizeInBytes\":0.0,\"RecursiveTriggersEnabled\":false,\"RemoteDataArchiveCredential\":\"\",\"LegacyCardinalityEstimation\":\"Off\",\"BrokerEnabled\":false,\"AutoShrink\":false,\"RemoteDataArchiveEnabled\":false,\"Protocol\":null,\"AutoCreateIncrementalStatisticsEnabled\":false,\"CatalogCollation\":\"DatabaseDefault\",\"RemoteDataArchiveLinkedServer\":\"\",\"QuotedIdentifiersEnabled\":false,\"AcceleratedRecoveryEnabled\":false,\"LocalCursorsDefault\":false,\"Credential\":{\"UserName\":\"xxx\",\"Password\":{\"Length\":0}},\"AutoUpdateStatisticsEnabled\":true,\"IsLedger\":false,\"DateCorrelationOptimization\":false,\"PageVerify\":\"Checksum\",\"MirroringWitness\":\"\",\"IsReadCommittedSnapshotOn\":false,\"LegacyCardinalityEstimationForSecondary\":\"Primary\",\"ParameterSniffing\":\"On\",\"ArithmeticAbortEnabled\":false,\"InstanceName\":\"MSSQLSERVER\",\"ChangeTrackingRetentionPeriod\":0}}"},"target":"dsc_lib::dscresources::command_resource","line_number":988}
{"timestamp":"2026-01-09T12:46:27.249614Z","level":"DEBUG","fields":{"message":"PID 224: jsonOutput={\"result\":[{\"name\":\"SqlServerDsc/SqlDatabase\",\"type\":\"SqlServerDsc/SqlDatabase\",\"properties\":{\"MirroringPartner\":\"\",\"OwnerName\":\"sa\",\"QueryOptimizerHotfixesForSecondary\":\"Primary\",\"MirroringTimeout\":0,\"CloseCursorsOnCommitEnabled\":false,\"ParameterSniffingForSecondary\":\"Primary\",\"RecoveryModel\":\"Simple\",\"AnsiPaddingEnabled\":false,\"ChangeTrackingAutoCleanUp\":false,\"IsSqlDw\":false,\"ReadOnly\":false,\"UserAccess\":\"Multiple\",\"RemoteDatabaseName\":\"\",\"NestedTriggersEnabled\":true,\"IsParameterizationForced\":false,\"DelayedDurability\":\"Disabled\",\"IsFullTextEnabled\":false,\"CompatibilityLevel\":\"Version160\",\"Trustworthy\":false,\"Port\":null,\"DefaultLanguage\":1033,\"AutoUpdateStatisticsAsync\":false,\"DatabaseOwnershipChaining\":false,\"MaxDop\":0,\"AutoClose\":false,\"EncryptionEnabled\":false,\"FilestreamNonTransactedAccess\":\"Off\",\"PrimaryFilePath\":\"S:\\\\MSSQL\\\\Data\\\\MSSQL16.MSSQLSERVER\\\\MSSQL\\\\DATA\",\"ChangeTrackingRetentionPeriodUnits\":\"None\",\"ChangeTrackingEnabled\":false,\"DefaultFullTextLanguage\":1033,\"Name\":\"model\",\"ConcatenateNullYieldsNull\":false,\"MirroringSafetyLevel\":\"None\",\"DataRetentionEnabled\":false,\"ServerName\":\"V-MSSQL176.xxx\",\"TargetRecoveryTime\":60,\"HonorBrokerPriority\":false,\"Reasons\":[],\"IsVarDecimalStorageFormatEnabled\":false,\"MaxDopForSecondary\":0,\"ContainmentType\":\"None\",\"QueryOptimizerHotfixes\":\"Off\",\"FilestreamDirectoryName\":\"\",\"NumericRoundAbortEnabled\":false,\"AnsiNullsEnabled\":false,\"TemporalHistoryRetentionEnabled\":null,\"MirroringPartnerInstance\":\"\",\"SnapshotIsolation\":false,\"PersistentVersionStoreFileGroup\":\"PRIMARY\",\"TwoDigitYearCutoff\":2049,\"Ensure\":\"Present\",\"AnsiNullDefault\":false,\"RemoteDataArchiveUseFederatedServiceAccount\":false,\"Collation\":\"Latin1_General_CI_AS\",\"AnsiWarningsEnabled\":false,\"AutoCreateStatisticsEnabled\":true,\"MirroringRedoQueueMaxSize\":0,\"RemoteDataArchiveEndpoint\":\"\",\"TransformNoiseWords\":false,\"MaxSizeInBytes\":0.0,\"RecursiveTriggersEnabled\":false,\"RemoteDataArchiveCredential\":\"\",\"LegacyCardinalityEstimation\":\"Off\",\"BrokerEnabled\":false,\"AutoShrink\":false,\"RemoteDataArchiveEnabled\":false,\"Protocol\":null,\"AutoCreateIncrementalStatisticsEnabled\":false,\"CatalogCollation\":\"DatabaseDefault\",\"RemoteDataArchiveLinkedServer\":\"\",\"QuotedIdentifiersEnabled\":false,\"AcceleratedRecoveryEnabled\":false,\"LocalCursorsDefault\":false,\"Credential\":{\"UserName\":\"xxx\",\"Password\":{\"Length\":0}},\"AutoUpdateStatisticsEnabled\":true,\"IsLedger\":false,\"DateCorrelationOptimization\":false,\"PageVerify\":\"Checksum\",\"MirroringWitness\":\"\",\"IsReadCommittedSnapshotOn\":false,\"LegacyCardinalityEstimationForSecondary\":\"Primary\",\"ParameterSniffing\":\"On\",\"ArithmeticAbortEnabled\":false,\"InstanceName\":\"MSSQLSERVER\",\"ChangeTrackingRetentionPeriod\":0}}]}"},"target":"dsc_lib::dscresources::command_resource","line_number":986}
{"timestamp":"2026-01-09T12:46:27.383110Z","level":"DEBUG","fields":{"message":"Process 'pwsh' id 224 exited with code 0"},"target":"dsc_lib::dscresources::command_resource","line_number":710}
{"timestamp":"2026-01-09T12:46:27.384475Z","level":"ERROR","fields":{"message":"Error: JSON: expected value at line 1 column 1"},"target":"dsc::subcommand","line_number":111}

DSC configuration

{
    "metadata": {
        "description": "SQL Server 2022 Installation on V-MSSQL176.xxx",
        "generated": "2025-11-04T15:42:28Z",
        "author": "Ansible DSC Automation",
        "target": "V-MSSQL176.xxx",
        "instance": "MSSQLSERVER"
    },
    "resources": [
        {
            "type": "SqlServerDsc/SqlDatabase",
            "name": "ConfigureModelDatabase",
            "properties": {
                "ServerName": "V-MSSQL176.xxx",
                "InstanceName": "MSSQLSERVER",
                "Name": "model",
                "RecoveryModel": "Simple",
                "Ensure": "Present",
				"Credential": {
				  "userName": "xxx",
				  "password": "xxx"
				},				
            }
        }
    ],	
    "$schema": "https://raw.githubusercontent.com/PowerShell/DSC/main/schemas/v3.1/config/document.json"
}

Suggested solution

Readable error output

SQL Server edition and version

2022 Developer Edition

SQL Server PowerShell modules

SqlServerDsc-17.4.0-preview0023

Operating system

Edition	Windows Server 2025 Standard
Version	24H2
Installed on	‎18.‎09.‎2025
OS build	26100.7462
Experience	Windows Feature Experience Pack 1000.26100.275.0

PowerShell version

7.5.2

SqlServerDsc version

17.4.0-preview0023

[ognif]

I think the regression was between 17.4.0-preview0015 and 17.4.0-preview0016

My DSC is 3.1.2

[johlju]

The resource has been enhanced with new properties and refactored into a class-based resource instead of an older MOF-based resource type.

If you are using DSCv3 it sounds like this issue: PowerShell/DSC#833.

There are some output (information, warning or error stream) from the resource that DSCv3 cannot parse (yet).

[johlju]

This repo does not test the the resource in DSCv3 yet due to the above mentioned issue. Can you run Get, Test, and Set individually with tracing on i see where it fails? If it fails on Get there is no need to run the other methods, I wonder if it is possible to see what the actual problem is in the trace log. But might not show up there either (due to DSCv3 do not parse error stream yet).

[ognif]

Iam willing to help but I need some tutorial how to use the module with Set/Get/Test

[johlju]

See in the issue PowerShell/DSC#833, there is an example of running SqlRSSetup with get method with tracing, just change to SqlDatabase and switch parameters and set them to your parameter values. Then just change the method to set or test, if get passes.

[johlju]

Also, I saw there is a PR in DSCv3 repository to fix using PSCredential type - so parameter Credential might not work until that PR is merged and in a preview release. See PowerShell/DSC#1308. There also seem to be more to the configuration to use a PSCredential type, see configurations examples in that PR. 🤔

[johlju]

It was a helper function that output a verbose message, but no longer. When running through LCM that is not a problem, but DSCv3 does not support it yet.

[ognif]

I request an explanation. I have now reported a regression in the use of DSCv3 in the SqlServerDSC software for the second time, and no one seems to care.

In fact, I get the impression that the DSC community doesn't support DSCv3 and is only developing its modules according to the outdated LCM.

Is DSCv3 being ignored by the DSC community, or why are modules knowingly not being tested with DSCv3?

[johlju]

Sorry if I was unclear, SqlDatabase now works with DSCv3, the issue was an verbose message that was removed so it does not hit the DSCv3 bug in PowerShell/DSC#833. I added an integration tests in the above linked PR to verify it works: #2102

In fact, I get the impression that the DSC community doesn't support DSCv3 and is only developing its modules according to the outdated LCM.
Is DSCv3 being ignored by the DSC community, or why are modules knowingly not being tested with DSCv3?

DSCv3 is very new and the community is slowly progressing towards it (most of us do this on their free time) and DSCv3 slowly evolves as well.

DSCv3 have not worked correctly with class-based resources or MOF-based resource until recently (last few previews), I have had the PR to integration test SqlRSSetup since May 2025 (and we found bugs that has been fixed in DSCv3 during that time), and just now with latest version of DSCv3 it actual runs as expected. Even then there are still issues with using DSCv3 and class-based resources as shown in the comments with linked issue and PR's.

Why are modules knowingly not being tested with DSCv3.

You are very welcome, as you too are part of the DSC community, to send in PRs to help add resources to be tested with DSCv3 and convert older MOF-based resources to class-based resource so they can be used with more functionality in DSCv3 (like export functionality).