We believe it's important to clarify everything before we start writing the code.
First, we conduct a meeting with the customers and the team. Then, we define the key name of extension and prepare the Database ER Diagram. After that, we create a draft prototype and cross-verify the TYPO3 technical feasibility. Finally, we re-analyze business logic.

Now it's time to develop TYPO3 extensions based on the requirements. This involves preparing the basic files/folder structure of the extension and initiating the extension (if required) using EXT.extension_builder.

Then, we conduct a basic QA test of the extension. Once we have tested the extension, we remove EXT.extension_builder and demonstrate it to the customer.

In some cases, customers require custom backend modules to meet their specific needs. When this is necessary, we follow these steps:

• develop and test domain models;
• create a basic TYPO3 frontend plugin;
• register the custom backend module under the Web section;
• integrate UI/UX using HTML5, CSS3, and Bootstrap;
• establish TYPO3 Extbase controllers, models, and repositories
• utilize the TYPO3 fluid template engine to render the module.

Now it's time to import, activate, and test the plugin. To ensure optimal productivity and quality, we adhere to the latest coding trends, technologies and TYPO3 standards. We conduct TYPO3 security testing (such as SQL injection testing) and improve speed and performance of extension. 

To create a custom TYPO3 extension, we would need the following information from you:

• A document outlining the specific requirements for the extension
• The desired design and functionality of the extension
• The version of TYPO3 you want the extension to be compatible with
• Any references or examples that you may have for the extension

In case any of these details are not available, we are always open to discussing them with you over a call.

To upgrade a TYPO3 extension, we first upgrade the TYPO3 core and any compatible extensions using the Extension Manager.

If any extensions utilized are outdated versions from TER, we manually search for and download the extensions from TER, and install them via composer after performing a dependency check.

In situations where current extensions are not compatible, we have several solutions available:

1. If a specific extension is not functioning properly, we search for an alternative extension from TER.
2. If no extension is compatible with the latest version, we make efforts to make it compatible with the latest version.
3. If none of the above options work, we develop a custom extension to meet the exact requirements.