# Upgrade Fails Due to Foreign Key Constraint in the PAGETEMPLATES Table

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## Symptoms

Upgrade fails. The following appears in the atlassian-confluence.log:

Cannot add or update a child row: a foreign key constraint fails (confluencedb/#sql-214_69ba, CONSTRAINT FKBC7CE96A17D4A070 FOREIGN KEY (PREVVER) REFERENCES pagetemplates (TEMPLATEID))


## Cause

It means there is a row in the PAGETEMPLATES table where its prevver column does not exist in the templateid column. This is a constraint violation.

## Resolution

Always backup your data before performing any modifications to the database.

1. Roll back database to the previous state (before upgrade)

2. Search for the rogue row by running:

select * from pagetemplates where prevver not in (select templateid from pagetemplates);

3. Delete it after making a backup of your database:

delete from pagetemplates where templateid is in (select templateid from pagetemplates where prevver not in (select templateid from pagetemplates));

If you are using MySQL, the delete command above will fail. The work around is to delete the problematic template one by one:

delete from pagetemplates where templateid = <template_id>;

<template_id> is the value for templateid returned from the select query.