# URGENT: Upgrade to 4.2.1 \> Error viewing contact details

**URL:** <https://forum.mautic.org/t/urgent-upgrade-to-4-2-1-error-viewing-contact-details/23637>\
**Category:** Product Support\
**Tags:** mautic-4\
**Created:** [April 6, 2022, 1:45pm UTC](https://forum.mautic.org/t/urgent-upgrade-to-4-2-1-error-viewing-contact-details/23637 "2022-04-06T13:45:00Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![silavapi](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.mautic.org/silavapi/32/7424_2.png) [@silavapi](https://forum.mautic.org/u/silavapi)\
**Post date:** [April 6, 2022, 2:20pm UTC](https://forum.mautic.org/t/urgent-upgrade-to-4-2-1-error-viewing-contact-details/23637/2 "2022-04-06T14:20:04Z")

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It looks like you have not fully completed the upgrade.

See this thread which has the same error:

> [@Error after upgrading to 4.2 clearing cache fails and error: Unknown column last\_built\_date in field list](https://forum.mautic.org/t/error-after-upgrading-to-4-2-clearing-cache-fails-and-error-unknown-column-last-built-date-in-field-list/22866/4):
>
> Right - @tobsowo had a similar problem. Other than the usual ‘don’t update in the browser’ message, here’s what helped him: Clear the cache by deleting the cache folder Follow these steps:

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_[View the full topic](https://forum.mautic.org/t/urgent-upgrade-to-4-2-1-error-viewing-contact-details/23637)._