IMPORTANT: On certain (older) TVs a software upgrade is not possible. In that case a "Software and Downloads" section will not be available on the Sony Support website.
Step 1: Check Sony Support website
1. Go to the Sony Support website and enter the applicable model name in the Find Support search engine.
2. On the specific model page, click the Downloads tab, select Software and Downloads and click the software / firmware icon to access the download procedure.
3. In this procedure you will see a section About this donwload. Here you can find the latest software / firmware version number.
For example: https://www.sony.co.uk/support/en/content/cnt-dwnl/prd-tvhc/bravia-kdlex-firmware-update-v6014/KDL-42EX440
Step 2: Check your TV
NOTE: In the software / firmware download procedure on the Sony Support website there will normally be a section Do I need to update, which you can follow to find the current TV software / firmware version number. In case this information would not be present, you can always follow below steps. Please note that the procedure may be slightly different for your specific model.
1. Power on the TV set and press the HOME or MENU button on the remote commander to display the Home menu.
2. Navigate to the Product Support and press OK.
3. Navigate to System Information and select it.
4. The version number is shown on the Software Version row. If the number is lower than the one on the Sony Support site, updating is needed.