logging successfully to admin results in 500 - An error has occurred

[dumbdoonan]

The front end of this long-forgotten site (which is about to undergo a redesign) is mostly fine, with some pages reporting:
You are not authorized to view this resource.

After successfully logging in to the administrator, the following error message is displayed:
500 - An error has occurred.
Return to Control Panel

Using phpmyadmin to Check Table returned the following:
The indexes ComponentId and ComponentId_2 seem to be equal and one of them could possibly be removed.

Using phpmyadmin to Optimize Table and Repair Table both returned zero errors or warnings.

Running those 3 + deleting the ComponentId_2 index failed to resolve the 500 error.

Advise gratefully accepted on how to fully access the Joomla Dashboard

David

[Per Yngve Berg]

Enable Error Reporting and Debug in Configuration.php

What version of php are the server running? Shall not be newer than 5.6

[dumbdoonan]

php had been running version 7.4 Downgrading to 5.6 results in the following error for the front end and back end:

Database connection error (1): The MySQL adapter 'mysqli' is not available.Database connection error (1): The MySQL adapter 'mysqli' is not available.


-----------------------------------------
Below is the result from enabling Error Reporting & Debug with php reset to 7.4, 7.3, 7.2, etc

500 - An error has occurred.
Return to Control Panel

Call stack
# Function Location
1 JAdministrator->dispatch() /home/thhourre/public_html/administrator/index.php:46
2 JError::raiseError() /home/thhourre/public_html/administrator/includes/application.php:164
3 JError::raise() /home/thhourre/public_html/libraries/joomla/error/error.php:251
Joomla! Debug Console
Errors

JFolder::create: Could not create directory Path: /home2/thhourre
Call stack
# Function Location
1 JAdministrator->dispatch() JROOT/administrator/index.php:46
2 JComponentHelper::renderComponent() JROOT/administrator/includes/application.php:153
3 JComponentHelper::executeComponent() JROOT/libraries/joomla/application/component/helper.php:348
4 require_once() JROOT/libraries/joomla/application/component/helper.php:380
5 JController->execute() JROOT/administrator/components/com_login/login.php:19
6 LoginController->login() JROOT/libraries/joomla/application/component/controller.php:761
7 JAdministrator->login() JROOT/administrator/components/com_login/controller.php:57
8 JApplication->login() JROOT/administrator/includes/application.php:234
9 JApplication->triggerEvent() JROOT/libraries/joomla/application/application.php:748
10 JDispatcher->trigger() JROOT/libraries/joomla/application/application.php:642
11 JEvent->update() JROOT/libraries/joomla/event/dispatcher.php:161
12 plgSystemLog->onUserLoginFailure() JROOT/libraries/joomla/event/event.php:71
13 JLog->addEntry() JROOT/plugins/system/log/log.php:41
14 JLog->addLogEntry() JROOT/libraries/joomla/log/log.php:346
15 JLoggerFormattedText->addEntry() JROOT/libraries/joomla/log/log.php:382
16 JLoggerFormattedText->initFile() JROOT/libraries/joomla/log/loggers/formattedtext.php:137
17 JFolder::create() JROOT/libraries/joomla/log/loggers/formattedtext.php:237
18 JFolder::create() JROOT/libraries/joomla/filesystem/folder.php:188
19 JFolder::create() JROOT/libraries/joomla/filesystem/folder.php:188
20 JError::raiseWarning() JROOT/libraries/joomla/filesystem/folder.php:263
21 JError::raise() JROOT/libraries/joomla/error/error.php:276

Call stack
# Function Location
1 JAdministrator->dispatch() JROOT/administrator/index.php:46
2 JError::raiseError() JROOT/administrator/includes/application.php:164
3 JError::raise() JROOT/libraries/joomla/error/error.php:251


------------------

Opening ticket with host re:
JFolder::create: Could not create directory Path: /home2/thhourre

[Per Yngve Berg]

You have to load the mysqli client in php.