Failed to reduce the GI file cache size below the current maximum Unity 2020

Failed to reduce the GI file cache size below the current maximum. Clear the cache or increase the maximum cache size in the Editor Preferences.

To fix this go into Edit > Preferences > GI Cache and you will need to increase your maximum cache size.

You can also set a custom cache path so if you have a storage HDD or an SSD you can offload your GI data cache to another drive that has plenty of space. In the following example, I have changed the path that my cache is stored in as well as increase the limit.