Note: the original release files for q2-sample-classifier contained a minor bug discovered by @LenaLapidot. This bug has been patched in the latest environment files, but users who installed QIIME 2 version 2019.7 prior to 19:00:00 UTC may be affected.
If you believe you are affected, there is no need to re-install unless if you plan to use q2-sample-classifier. This bug does not affect data integrity, it only causes the classify-samples pipeline to crash if you are attempting to classify sample data that only has two classes (types). If you have no clue what that means, then you probably don’t need to re-install.
Thank you @LenaLapidot for swiftly discovering this bug! 
