collected the logs
[Wed Mar 21 18:53:35.969970 2018] [:error] [pid 4877] [client 176.127.24.146:64990] Default exception handler: Your session has most likely timed out. Please log in again. Debug: \nError code: invalidsesskey\n* line 482 of /lib/setuplib.php: moodle_exception thrown\n* line 56 of /admin/oauth2callback.php: call to print_error()\n
[Wed Mar 21 18:54:00.667945 2018] [:error] [pid 32163] [client 176.127.24.146:64997] Default exception handler: Your session has most likely timed out. Please log in again. Debug: \nError code: invalidsesskey\n* line 482 of /lib/setuplib.php: moodle_exception thrown\n* line 56 of /admin/oauth2callback.php: call to print_error()\n, referer: http://MYSITE/moodle/login/index.php
[Wed Mar 21 18:54:07.064678 2018] [:error] [pid 5591] [client 176.127.24.146:64999] Default exception handler: Sorry, the requested file could not be found Debug: \nError code: filenotfound\n* line 482 of /lib/setuplib.php: moodle_exception thrown\n* line 1885 of /lib/filelib.php: call to print_error()\n* line 2061 of /lib/outputlib.php: call to send_file_not_found()\n* line 59 of /theme/lambda/lib.php: call to theme_config->setting_file_serve()\n* line 4803 of /lib/filelib.php: call to theme_lambda_pluginfile()\n* line 40 of /pluginfile.php: call to file_pluginfile()\n, referer: http://MYSITE/moodle/?
[Wed Mar 21 18:54:15.236204 2018] [:error] [pid 3025] [client 176.127.24.146:65001] Default exception handler: Sorry, the requested file could not be found Debug: \nError code: filenotfound\n* line 482 of /lib/setuplib.php: moodle_exception thrown\n* line 1885 of /lib/filelib.php: call to print_error()\n* line 2061 of /lib/outputlib.php: call to send_file_not_found()\n* line 59 of /theme/lambda/lib.php: call to theme_config->setting_file_serve()\n* line 4803 of /lib/filelib.php: call to theme_lambda_pluginfile()\n* line 40 of /pluginfile.php: call to file_pluginfile()\n, referer: http://MYSITE/moodle/?
[Wed Mar 21 18:54:15.624502 2018] [:error] [pid 5591] [client 176.127.24.146:64999] Default exception handler: Sorry, the requested file could not be found Debug: \nError code: filenotfound\n* line 482 of /lib/setuplib.php: moodle_exception thrown\n* line 1885 of /lib/filelib.php: call to print_error()\n* line 2061 of /lib/outputlib.php: call to send_file_not_found()\n* line 61 of /theme/lambda/lib.php: call to theme_config->setting_file_serve()\n* line 4803 of /lib/filelib.php: call to theme_lambda_pluginfile()\n* line 40 of /pluginfile.php: call to file_pluginfile()\n, referer: http://MYSITE/moodle/?
but the files are there:
/var/www/html/moodle/theme/lambda
-rw-r--r-- 1 apache apache 6.4K Mar 21 18:52 config.php
-rw-r--r-- 1 apache apache 31K Mar 21 18:52 lib.php
-rw-r--r-- 1 apache apache 970 Mar 21 18:52 renderers.php
-rw-r--r-- 1 apache apache 46K Mar 21 18:52 settings.php
-rw-r--r-- 1 apache apache 1.3K Mar 21 18:52 version.php
(ignore timestamp - i've just updated them into a pathetic attempt)