How do I fix these annoying errors that pop up while using Cydia?
If you've just installed Cydia on your device and you see "cannot locate package" errors, close Cydia and open it again, and then wait for it to finish downloading and loading data.
If you see "untrusted server certificate" or "an SSL error has occurred" preventing you from using Cydia, check to make sure your device's date is set correctly (using your device's Settings app).
If your device finishes reloading data and then pops up a black screen including red and yellow errors, they usually indicate a problem with one of the repositories you have installed (or sometimes one of the packages). Cydia is still working fine, but you may want to try refreshing data again or removing the broken repository. Keep in mind that Cydia has no control over third-party repositories. Common repository (source) errors include:
"Failed to fetch": This usually happens when a source does not exist. You may have typed in the wrong URL, the source may have shut down, or the source may be broken. This is often a temporary problem, so wait a few hours and try reloading data again. If it keeps happening, look carefully at the error message to find the URL of the broken repository, and then you can choose to remove that repository by going to Manage, tapping Sources, and tapping Edit. (On iPad, tap Sources and then Edit.) If the source can't be removed that way, it may have been installed as a package, which means you need to uninstall that repository package.
"POSIX error: Operation Timed Out": Make sure your device has access to the internet and try again. If this error keeps happening, it is likely caused by a repository server being temporarily offline. Try again later. You can also choose to remove the repository (see the method above).
"GPG error": This means that a repository is configured incorrectly. You can usually safely ignore this.