How to fix a “PHP Warning: igbinary_unserialize_header: unsupported version: ….” error (TYPO3)

I got this error after setting up a TYPO3 7.6.32 project on my local machine.

Solution

Clear the cache.

Follow steps below to clear the cache

• Enter the Install Tool at https://example.com/typo3/install on your TYPO3 website. Use Install Tool because the backend will also give this error when you try to access it.
• After logging in, click on the Clear all cache button.

After cache successfully cleared, try opening the frontend or backend of your website and the error should be gone.