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How to Fix Access Pass-Through Query Error 3305 Invalid Connection String

Khadija Khan Oct 7, 2026 868 views

Question details

Users encounter error 3305 regarding an invalid connection string when executing VBA pass-through queries in Access.

Fixing Access Pass-Through Query Error 3305 (Invalid Connection String)

Product: Microsoft Access
Device & OS: Windows
Scenario: Executing a VBA pass-through query that relies on an ODBC connection string after installing a recent system update.
Observed behavior: The database returns Error 3305 'Invalid Connection String', and the query fails even when the connection string is directly supplied.

Before you start

Verify your current Microsoft Access version, build number, and update channel by navigating to File > Account before attempting to apply any updates.

Solution 1Recommended

Update Microsoft 365 to the Latest Channel Release

This error is linked to a known bug introduced in a previous update. Installing the latest patch from the Current Channel will resolve the issue automatically.

Microsoft has acknowledged this bug affecting VBA pass-through queries and ODBC connection parsing. A permanent fix has already been rolled out to users on the Current Channel.

Open Account Settings

Launch Microsoft Access, click on 'File' in the top-left corner, and select 'Account' from the menu.

Check for Updates

Under the Product Information section, click on the 'Update Options' dropdown menu.

Apply Updates

Select 'Update Now'. Allow Microsoft 365 to download and install the latest patches.

Restart Access

Once the update is complete, close and restart Microsoft Access, then run your VBA pass-through query again.

Update Microsoft 365 to the Latest Channel Release

Automatic Updates: Ensuring your Microsoft 365 installation is set to update automatically can prevent similar known bugs from affecting your workflow in the future.

Solution 2

Verify ODBC Connection String Syntax

Ensure that your connection string is formatted correctly and includes all required delimiters, as syntax errors can mimic update bugs.

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Frequently Asked Questions

Why did my VBA pass-through query suddenly stop working?

A specific Windows and Microsoft 365 update introduced a bug that affects how Access processes ODBC connection strings in DAO, leading to Error 3305.

How do I check my Microsoft Access update channel?

Open Access, click on 'File', navigate to 'Account', and look under the 'About Access' section to see your version, build number, and current update channel.

Can a missing semicolon cause Error 3305?

Yes, ODBC connection strings require precise formatting. A missing semicolon between parameters will cause Access to misinterpret the string and return an invalid connection string error.

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