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VectleSkillsAtlas error: transaction numbers are only allowed on a replica set member or mongos

Atlas error: transaction numbers are only allowed on a replica set member or mongos

Export

You are talking to a single node instead of the replica set, usually because of directConnection. Fix the string, not the transaction code.

"Transaction numbers are only allowed on a replica set member or mongos"

This error means the driver connected directly to one mongod and bypassed replica set semantics. Transactions need the replica set (or mongos).

Confirm

  1. Check the connection string for directConnection=true. That option pins the driver to a single host and disables replica set behavior. It is the usual culprit.
  2. Check for a standard-form string listing only one host without replicaSet=....
  3. Some tools and GUIs add directConnection=true silently when you pick a "direct connection" mode.

Fix

Remove directConnection=true and, for standard-form strings, include the full host list plus replicaSet=[name]. The SRV string handles this automatically. Keep retryWrites=true.

Verify

Run a trivial multi-document transaction (insert two docs, commit). Success proves replica set semantics are back.

Maintainer review

No maintainer verification is recorded for this version.

This records the version a maintainer checked. It does not assert that the version is the latest upstream release.

Technical Details
Use when
No specific conditions
Published by
issueatlas
Published
Skill ID
skl_AmTD82bvZLcPKR0rlfeezg
Version ID
skv_673D8mVKqGIrI-75zNCrPg
Version History & Decisions

Version History & Decisions

Published version

Published guidance. View the version history for earlier changes.

More public guidance matched to this skill.

"cannot execute in a read-only transaction": you are on the replicaSymptom: writes fail with "cannot execute INSERT in a read-only transaction" (SQLSTATE 25006). Cause: the connection string points at a read replica. Fix: route writes to the primary.Read skill →Error: "Only async functions are allowed to be exported in a 'use server' file"Error: "Only async functions are allowed to be exported in a 'use server' file": I had a similar issue in next 14 where I was using an index.ts file to centralize my exports of server actions.Read skill →Materialize write only transactions must hit one table or commit failsKeep write-only transactions to one table. In Materialize every INSERT inside a single transaction block must hit the same table as the first INSERT, or COMMIT dies with 'internal error, wrong set of locks acquired' and rolls back everything. The fix is to split multi-table writes into separate transaction blocks rather than assuming Postgres-style multi-table transactions.Read skill →

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Published recentlyPublished Sep 26, 2026. This reminder uses publication date only; it does not mean the content was verified. Review again after Mar 25, 2027.

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