Invalid JSON logs produced for function apps - V5 runtime release and fix

Question

Invalid JSON logs produced for function apps - V5 runtime release and fix

Leanne Bayliss 0

Hi,

Can you assist,

The Azure Function App diagnostic logs are successfully being ingested into Google SecOps (MxDR). However, the properties field within the FunctionAppLogs category is being emitted in a non-standard format that prevents native parsing and field extraction. Specifically, the field contains single-quoted key/value pairs rather than valid JSON. [learn.microsoft.com], [github.com]Invalid JSON logs produced for function apps.

I cannot find a published Microsoft source confirming:

that the issue has been fixed,
that engineering is actively developing a fix,
that the fix is definitively scheduled for Runtime V5,
or any ETA for delivery.

Thank you

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Answer 1

Hello @Leanne Bayliss

Based on the currently published information, I don't think it's accurate to say this is confirmed fixed or scheduled for Azure Functions Runtime V5.

The original Microsoft Q&A thread confirms the behavior where FunctionAppLogs.properties is emitted using single quotes, making the field invalid JSON for downstream parsers. A later comment referenced an Azure Functions team statement that it would be addressed as a breaking change in Runtime V5, but explicitly said: “No ETA yet.”

More importantly, Microsoft's current Functions runtime documentation still states that Azure Functions currently supports only runtime version 4.x. There is no published GA V5 release or migration schedule to provide a reliable delivery date for this fix.

For now, treat the V5 statement as an engineering intention rather than a committed release date. For production ingestion into Google SecOps, you should continue using a parsing/transformation workaround rather than planning around an unannounced V5 release.

If you require confirmation of whether this specific logging change is still on the V5 backlog, I recommend opening an Azure Functions support case and referencing the original issue. Microsoft Support/Functions engineering is the appropriate source for an internal status or ETA that hasn't been publicly documented.

Reference: Microsoft - Azure Functions runtime versions

So, for now: the issue is documented; V5 was mentioned as the intended fix point, but I can't find a publicly confirmed fix, V5 release date, or ETA.

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