Miss_B

I have developed an app that will do just that. 
https://www.yourforumservices.com/index.php?/topic/23-modcp-validating-members-management/#comment-23

I am a little confused. That is precisely what the approval queue does. The moderated content will be visible to the general public only after someone has approved them.

Have a look at my post at this other topic where another member had a similiar issue like you.
 

That would be the best course of action, but from what I read, it appears that the OP doesn't have access to the email address anymore, that they had used for the admin account. In that case doing a password reset won't help much I am afraid. But maybe I read it wrong.
 

Are you on a shared hosting plan or do you manage your own Vps/Dedicated box?
If the former, then there is nothing that you can do about it. Some hostsmay choose to disable the PHP function phpinfo() for security reasons, because it displays information which may be used to compromise the server that your site is running on. In that case you should contact your host and ask them if they can enable it.
If the later, at the php.ini file find the following line: (it's located athe disable_functions directive)
disable_functions = phpinfo 
and change it to disable_functions = and save the changes. That should enable phpinfo. Hope it helps.
 

You will need indeed a custom app for that. It's fairly easy to do. 

What version of Ipb do you have and what is your php version?
Have you upgraded your forum since you deactivated the calendar? If you did so and you didn't upload the calendar files as you didn't plan to use it, can you reupload the calendar files as well and overwrite the current files and see if the error will go away? The error might occur due to the calendar files being out dated and not compatible with the php version.

It looks like an incorrect path issue. The path where session_start() attempts to write its data to is not correct. The session.save_path should be entered correctly at the php.ini.
You can use the tool below to check.
Yes, provided it meets the requirements. 
 

Most likely they are not compatible with your php and/or forum version. And yes, they will need to either be recoded or upgraded.

It is a group permission. It can be found under the Social->Messages->Conversations allowed to start per day.

In that case the only option is to post the topics manually.
 
If you want to change the topic starters and start date, I have developed an app for that. You can see it here:
 
@Adriano Faria has another similiar app that changes the posts date. You can see it here:
 
 

it is a moderator permission. You can find it under the Content tab. For more please see the attached screenshot.

This can be marked as solved. @Jason Back contacted me and I upgraded the forum successfully to the latest version running on php 8.

Do you have strict sql mode enabled?  Somewhere an empty string ''  is being passed as a value for decimal fields in the insert query. If strict sql mode is enabled and an invalid data is inserted into a column, it throws an error rather than providing a warning.
I 've come this across before. I fixed it by changing the INSERT query to add the IGNORE command. 
i.e. from INSERT INTO table_name to INSERT IGNORE INTO table_name
Hope it helps.

Broken how?
 
Are you sure that you have overwritten your forum files correctly? To me this looks like a case of files not being uploaded in the right location.
There is no need for a fresh install imo. When you run the installer you are presented with an option to enter the prefix. It looks like you did not enter one, hence why there were no prefixes added to the database.
That being said, it looks like you have several tables in that database. You should check the sql_tbl_prefix vale at conf_global.php file. That holds the prefix for your Ipb forum. The tables prefecased with that prefix are the one that you need. Hope it helps.
 

You can run a sql query for that.
SELECT tid, title FROM `forums_topics` WHERE poll_state = 1;
That will list the topic id and title of all topics with polls. Hope it helps.

Have a look at my app. It does just that. 
 

You can edit the relevant language string. I can not remember it off the top of my head but you can search for it in the Languages section of your Admin Panel. Hope it helps.

That will require a custom plugin/app. You can request it here:
https://invisioncommunity.com/forums/forum/506-requests/
 

For number 1, if you go the forums section in your Admin Panel and then clcik the drop down icon for the Category whose topics you want to delete, you will see an option that says: Move / Delete Content. There you can delete all the topics. 

What happens if you use the color instead of html? And the font tag has been depricated for a while btw. 
 

You can use the Contact Us link at the bottom. 
https://invisioncommunity.com/contact-us/

Change the value of member_group inside the conf_global.php file to the id of the group that you want your new members to have by default when registering.

I do not remember seen any such plugin. Have a look at the Marketplace btw. If there is such plugin, it will be there. 
If there is not any, you can request one in the request forum.

I am not familiar with that app. You can ask at its support topic about that.
I found another one that I think it would be better suited for you, by @Adriano Faria.