I have a fresh install of CiviCRM (5.27) running on a Google Cloud Server Debian buster.
System is fully updated WordPress is 5.4.2
I wish to use Geocoding and of course noticed it is not in the searchable list of extensions.
I went to the download page and see that it says 5.26 - the documentation here leads me to believe that means "at least 5.26" so 5.27 should (in my mind - and correct me if I am wrong) be ok.
I put the zip file in the ext directory and changed the ownership to www-data:www-data and unzipped.
I refreshed extensions loader and saw it there and pressed install and then got a blank screen (civicrm themed so not a WP error) saying my wordpress install had a critical error.
Refreshing the page still shows the option to install and everything else works.
I hope I have given sufficient detail and am prepared to do any level of debugging.
I did not wish to try anything in case anyone wishes to see this error pristine (I did try install one second time).
Thank you,
Karl
PS, here is an error log entry:
[Tue Jul 07 00:57:43.003646 2020] [php7:error] [pid 26414] [client 107.143.245.58:56972] PHP Fatal error: require( ): Failed opening required '/var/www/html/civiwalk.com/wp-content/plugins/civicrm/civicrm/ext/org.wikimedia.geocode r-1.4/vendor/composer/../symfony/polyfill-mbstring/bootstrap.php' (include_path='.:/var/www/html/civiwalk.com/wp-co ntent/plugins/civicrm/civicrm:/var/www/html/civiwalk.com/wp-content/plugins/civicrm/civicrm/packages:/var/www/html/ civiwalk.com/wp-content/plugins/civicrm/civicrm/vendor/tecnickcom:/var/www/html/civiwalk.com/wp-content/plugins/civ icrm/civicrm/vendor/phpseclib/phpseclib/phpseclib:/var/www/html/civiwalk.com/wp-content/plugins/civicrm/civicrm/ven dor/pear/pear_exception:/var/www/html/civiwalk.com/wp-content/plugins/civicrm/civicrm/vendor/pear/auth_sasl:/var/ww w/html/civiwalk.com/wp-content/plugins/civicrm/civicrm/vendor/pear/log:/var/www/html/civiwalk.com/wp-content/plugin s/civicrm/civicrm/vendor/pear/console_getopt:/var/www/html/civiwalk.com/wp-content/plugins/civicrm/civicrm/vendor/p ear/pear-core-minimal/src:/var/www/html/civiwalk.com/wp-content/plugins/civicrm/civicrm/vendor/p in /var/www/html/c iviwalk.com/wp-content/plugins/civicrm/civicrm/ext/org.wikimedia.geocoder-1.4/vendor/composer/autoload_real.php on line 66, referer: http://www.civicafe.com/wp-admin/admin.php?page=CiviCRM&q=civicrm%2Fadmin%2Fextensions&action=add &id=org.wikimedia.geocoder&key=org.wikimedia.geocoder