Size mismatch errors are something that seem to plague me every once in a blue moon when I try to install a jailbreak tweak right after an update is released, or after Cydia refreshes its sources.
The issue can occur when Cydia tries to fully refresh its sources at the time of a repository sync, and I'm sure some of you have probably stumbled upon this same error one time or another.
If you ever do get a size mismatch error in Cydia, we'll be explaining in this short tutorial how you can fix the problem and install the jailbreak tweak you want to download once and for all.