When you’re trying to open your SSIS or SSRS solution, you will get a message that the migration has failed or ‘The application which this project type is based on was not found.‘

From https://www.jonashendrickx.com/2017/06/26/cannot-open-ssrsssis-projects-vs2017/ 

Method 1

1. Open ‘Microsoft Visual Studio 2017‘.
2. In the menu bar, expand ‘Tools‘, then choose ‘Extensions & Updates‘. to install an extension.
3. Search for ‘Microsoft Reporting Services Projects‘, and install this extension.
4. To complete the installation, shut down all windows and instances of Microsoft Visual Studio 2017. Then the installer will start.
5. Try to open your solution or projects (*.rptproj) again.

Method 2

1. Close all windows and instances of ‘Microsoft Visual Studio 2017‘.
2. Download ‘Microsoft Reporting Services Projects‘ from the Visual Studio marketplace.
3. Open your solution or project.

From here: http://www.isolutionspartners.com/sql-reporting-services-error-maximum-request-length-exceeded/

You could, quite honestly, run into this error in a lot of situations involving a web app, but we’re talking specifically about SSRS in this post. The basic problem here, is that your posting an amount of data to a web app larger than it is configured to accept.  Hence, it is throwing an error.

It’s an easy fix though.  You’ve got to adjust the web.config for the web app, which in the case of reporting server, is usually somewhere like this:

For SQL Server 2012: C:\Program Files\Microsoft SQL Server\MSRS11.MSSQLSERVER2012\Reporting Services\ReportServer

Find the web.config file for your reporting services instance, open it up, and track down the line that looks something like this

executionTimeout = "9000" />

Now just add a max request length attribute in there to fix the problem, adjust your size as needed.  This is 5meg.

executionTimeout = "9000" maxRequestLength="500000" />

And now you’ll need to restart IIS.  start->run->”iisreset”

From: https://msdn.microsoft.com/en-us/library/dd207045.aspx

In this scenario, it can be many reasons to cause this problem, even the current user has enough authority to do anything on Report Manager. Please try to do trouble shooting as below:

1. Run the browser as an Administrator.
2. Add the Report Manager URL as Compatibility View settings.
3. Use http://<servername>/reports instead of using Localhost.
4. If the steps above still can't make you see the dropdown menu, it might caused by corrupt reportingservices.js file. Please try to restore this file on server.

https://popbi.wordpress.com/2012/08/21/ssrs-toggle-visibility-show-initially-as-expanded/

‎Reporting Services provides some nice options to allow user’s to feel like they are interacting with the data, by expanding lower levels of detail when they click on the plus (+) sign in the report’s tablix. You can also set the initial Toggle state of report items as expanded i.e. (-) sign.  There is a catch though in that when you Show your initial state as expanded, the items may expand correctly but the toggle sign appears reversed (i.e. +  instead of -).

Nice solution to the problem demonstrated Here.