I get the following message when doing a clean install on M4.0. I just think it's because a permission check is being run before the plugin is fully installed, so probably not too serious.
Capability "block/quickmail:myaddinstance" was not found! This has to be fixed in code. ++
* line 453 of /lib/accesslib.php: call to debugging()
* line 194 of /blocks/quickmail/classes/plugin.php: call to has_capability()
* line 133 of /blocks/quickmail/classes/plugin.php: call to block_quickmail_plugin::user_has_capability()
* line 87 of /blocks/quickmail/block_quickmail.php: call to block_quickmail_plugin::user_can_send()
* line 376 of /blocks/moodleblock.class.php: call to block_quickmail->applicable_formats()
* line 1006 of /lib/upgradelib.php: call to block_base->_self_test()
* line 584 of /lib/upgradelib.php: call to upgrade_plugins_blocks()
* line 1935 of /lib/upgradelib.php: call to upgrade_plugins()
* line 202 of /admin/cli/upgrade.php: call to upgrade_noncore()
* ```
I get the following message when doing a clean install on M4.0. I just think it's because a permission check is being run before the plugin is fully installed, so probably not too serious.