HTTP and Upstash log transports mutate caller-owned records

HTTP and Upstash log transports write a timestamp onto the caller's log object. Frozen records fail with TypeError: Cannot add property time, object is not extensible and are not buffered.

Difficulty

Easy

Time

~5 min

Steps

Fixed in

@mastra/core@1.77.0

Last checked

Oct 19, 2026

Verified fix: PR #26892 merged on 2026-10-13. Fixed in @mastra/core@1.77.0 (first published release whose tag contains the merge commit). Last checked 2026-10-19.

Symptom

HTTP and Upstash log transports write a timestamp onto the caller's log object. Frozen records fail with TypeError: Cannot add property time, object is not extensible and are not buffered.

Evidence what you'll see

After HttpTransport.write({ msg: 'caller-owned record' }) the same object gains a time field. The expected object is unchanged.
JSON-string input does not share the caller's object and is unaffected. Records whose timestamp is explicitly undefined or null are also mutated.
No service is contacted in the reproduction: the record stays below the batch threshold and the buffer is cleared before destruction.

Why it happens

HttpTransport and UpstashTransport assigned time on the object passed in. Pull request 26892 adds time on a shallow copy used only for buffering, and leaves records that already have a timestamp, including 0, unchanged.

Affected versions

@mastra/loggers workspace source 1.3.6. Node.js 24.21.0, pnpm 11.21.0, Linux. No live logging service is required.

Fix steps

0 of 2 done

Step 1Upgrade to a tree that contains pull request 26892. The first published tag that contains that merge is @mastra/core@1.77.0.
Step 2The linked issue does not give a transport option that copies the record on @mastra/loggers 1.3.6.

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How to check it worked

Writing a plain object without time leaves that object unchanged, and a frozen record is buffered instead of throwing Cannot add property time, object is not extensible.

If it still fails

The original chunk is still passed through. JSON-string input was already a copy. The linked issue does not describe the TypeError on a tree that contains pull request 26892.

Sources and credit

Summarized in our own words from these public reports. Credit goes to their authors.

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