When manually upgrading Joomla through the extensions manager, I get the following error:

500 error

Installation unexpectedly terminated:Refresh Manifest Cache failed: Extension is not currently installed.

I was upgrading from Joomla 2.5.18 to 2.5.20. I believe this also happened when I upgraded a different site from 2.5.18 to 2.5.19. After upgrading, I checked the Joomla version. It says 2.5.20. I checked ExtensionsManager -> Warnings There were none. I checked ExtensionsManager -> Database

It showed

Database table structure is up to date.
Database schema version (in #__schemas): 2.5.20. Update version (in #__extensions): 2.5.20. Database driver: mysqli. 66 database changes were checked successfully. 41 database changes did not alter table structure and were skipped

My questions

  1. What is the Refresh Manifest Cache?
  2. Why is it causing the error? (I.E. What extension is likely to not be installed?)
  3. Is my installation safe? Should I upgrade again using the same upgrade package?
  • "Purge Cache" no longer exists in the Joomla 3 Extentions/Discover page.
    – Kimo
    Commented Apr 20, 2021 at 19:59

2 Answers 2

  1. The manifest cache is a field in the #__extensions table which holds the informations from the extension manifest file (the xml file describing the extension and what to install). You can refresh it as well in the extension manager using the refresh cache button.

  2. I don't know where the error is coming from, otherwise I would fix it :-)

  3. I'd say it's safe. The refreshing happens after the update was completed.


I thought I would extend on Bakual's answer.

What is the Refresh Manifest Cache?

According to https://www.akeebabackup.com/support/admin-tools/15271-refresh-manifest-cache-failed.html

it detects database errors and fixes them. It's for when the update reports errors.

What's causing it? How can I fix it?

  1. Login to Joomla Admin. Go into Extension Manager ->Discover -> Purge Cache
  2. Then go into Extension Manager -> Database -> Fix
  3. Next go into Extension Manager -> Discover -> Discover
  4. Lastly install the found extensions/plugins/modules

The problem should go away after doing the above process.

Is my installation safe? As Bakual pointed out it should be ok. I've not encountered any errors since updating and in one of the links below the developer said of the problem- it's

Nothing overly serious.

My information was obtained from

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