TYPO3: No template was found. View could not be resolved for action - typo3

Question

I'm experimenting a bit with TYPO3 backend modules and I'm trying to get a view when I click my module in the left menu in the backend. However when I click this I get the following message:
Sorry, the requested view was not found.
The technical reason is: No template was found. View could not be resolved for action "list" in class "MyVendor\MyModule\Controller\ConnectionController".
I have the view for the list action in the folder Resources/Private/Backend/Templates/Connection and the file is called List.html (uppercamelcase)
I'm using TYPO3 version 7.6.15 and I made this module with the extension builder.
Any help would be appreciated.

Answer 1

Some possible reasons for this (or similar) errors:
1. Forgetting to include the TypoScript static templates
see Documentation: Include TypoScript from extensions
Choose WEB > Template module (in Module menu)
Select your start (root) page (in page tree)
Select Info / Modify (in Docheader)
Choose Edit the whole template record
Choose tab Includes
Select your extension under Available Items
This will activate the TypoScript under Configuration/TypoScript
2. Wrong path
The Template paths set via TypoScript must match the available template paths in the filesystem.
Usually, the default path is:
Resources/Private/Templates (for frontend plugins)
or
Resources/Private/Backend/Templates (for backend modules)
This must have been set correctly via TypoScript. For example:
Configuration/TypoScript/setup.typoscript:
# Module configuration
module.tx_myexample_web_myexamplelist {
view {
templateRootPaths.0 = EXT:myexample/Resources/Private/Backend/Templates/
...
module. is for backend modules
if you are working with frontend plugins, use plugin. instead of module.
the correct file ending for TypoScript is .typoscript since TYPO3 8 and no longer .ts or .txt. For version 7, it is correct to use .ts.
3. Incorrect filenames
Make sure that the name of the Controller matches the name of the subdirectory in the Templates directory. The name of the template file is capitalized.
Controller/SomeController.php: listAction()
matches
Resources/Private/Backend/Templates/Some/List.html
Where to define the TS:
either as described above e.g. in Configuration/TypoScript setup.typoscript (and load this via static include).
The file ext_typoscript_setup.typoscript in the extension root can be used to setup TypoScript independent of page-tree and template-records. This will be included in the setup section of all TypoScript templates. but also consider the warning in the documentation.
Load TypoScript or TypoScript files directly in the extension with functions from ExtensionManagementUtility

Answer 2

You can also change your template root path (the relative path from where the extension takes the tempaltes):
go to the
setup.ts
file (or setup.txt file; depends on personal preferences and local configuration) and add the following line
plugin.tx_myslider.view.templateRootPath = EXT:path/to/custom/directory/
for example it could look like this:
EXT:slider/Resources/Private/Templates/myAwesomeFolder/
NOTE: slider is just a placeholder. You can simply replace it with your extension name

Answer 3

Add your extension to the website node. Until you add it, the setup.ts won't work.