Unable to upgrade to 1.2.9

[deshmukh]

I am unable to upgrade from my current ABC installation of 1.2.8 to the latest ABC version 1.2.9.

The package installer returns a cryptic

Marketplace error: Error: ()
Stuck? Not a problem. You can install extensions another way. Check this help link.

error.

That help link just takes me to the FTP install extension in the documentation.

How do I upgrade?

[abolabo]

please use installation key

abantecart_upgrade_129

[morrisr]

Same problem
upgrading from 1.2.8 to 1.2.9 keeps spinning.
Using ssl, disabled cloudflare caching. cleared all cache. tried few times.
Store side - works fine.
Admin side - does not run most 9 out 10
error Log attached

[abolabo]

looks like you lost this file https://github.com/abantecart/abantecart-src/blob/master/public_html/storefront/controller/common/html_cache.php
Also try to disable all cache in admin/system/settings/system before upgrade