It's failing due to the following error.
Code:
Object of class CB\Database\Table\UserTable could not be converted to string in JROOT/libraries/joomla/database/driver/mysqli.php:254
Which is call stack traced as follows.
Code:
# Function Location
1 () JROOT/libraries/joomla/database/driver/mysqli.php:254
2 JDatabaseDriverMysqli->escape() JROOT/libraries/joomla/database/driver.php:1871
3 JDatabaseDriver->quote() JROOT/libraries/src/User/UserHelper.php:294
4 Joomla\CMS\User\UserHelper::getUserId() JROOT/libraries/src/User/UserWrapper.php:134
5 Joomla\CMS\User\UserWrapper->getUserId() JROOT/libraries/src/User/User.php:280
6 Joomla\CMS\User\User::getInstance() JROOT/libraries/src/Factory.php:266
7 Joomla\CMS\Factory::getUser() JROOT/components/com_comprofiler/plugin/user/plug_p8pbb/cb.p8pbb.php:875
8 p8pbbCBTab->newPassword() JROOT/libraries/CBLib/CB/Legacy/cbPluginHandler.php:880
9 cbPluginHandler->call() JROOT/libraries/CBLib/CB/Legacy/cbPluginHandler.php:1293
10 cbPluginHandler->trigger() JROOT/components/com_comprofiler/comprofiler.php:895
11 sendNewPass() JROOT/components/com_comprofiler/comprofiler.php:123
12 require_once() JROOT/libraries/src/Component/ComponentHelper.php:402
13 Joomla\CMS\Component\ComponentHelper::executeComponent() JROOT/libraries/src/Component/ComponentHelper.php:377
14 Joomla\CMS\Component\ComponentHelper::renderComponent() JROOT/libraries/src/Application/SiteApplication.php:194
15 Joomla\CMS\Application\SiteApplication->dispatch() JROOT/libraries/src/Application/SiteApplication.php:233
16 Joomla\CMS\Application\SiteApplication->doExecute() JROOT/libraries/src/Application/CMSApplication.php:225
17 Joomla\CMS\Application\CMSApplication->execute() JROOT/index.php:49
It's specifically caused by the following.
Code:
7 Joomla\CMS\Factory::getUser() JROOT/components/com_comprofiler/plugin/user/plug_p8pbb/cb.p8pbb.php:875
8 p8pbbCBTab->newPassword() JROOT/libraries/CBLib/CB/Legacy/cbPluginHandler.php:880
It's coming from your 3rd party CB plugin p8pbb (plug_p8pbb). Unpublishing it fixes the issue. Suggest contacting the developer of that plugin and having them fix it if you need that.