The update that Apple released a week ago, not only with the promise that the iPhone battery issues would finally be solved, but also that was supposed to bring a set of improvements to the iOS 5 experience, has maybe caused more problems than offered solutions.
According to an AppleInsider report, after updating to iOS 5.0.1, some users were mystified to see their iPhone 4S display messages like "Invalid SIM" and "SIM Failure". The error messages appear even if the iPhone operates on a CDMA network and does not use a SIM card.
One thread on Apple's support forum regarding the issue has had almost 40,000 views up till now.
Not only AT&T subscribers who make use of the SIM card slot in their iPhone experienced this kind of error, but also subscribers from Verizon and Sprint who can use the "roaming SIM" only when travelling aboard on local GSM networks.
Some iPhone 4S owners noticed similar problems in October after they received their new handset. A SIM related error means that the owners cannot use their iPhone for basic functions such as making phone calls, sending text messages, and using mobile data.
The suggested solution for this error message is to reboot the iPhone, as other attempts like restore or removal of the SIM seem to fail to solve the problem.
iPhone owners will be hoping that iOS 5.0.2, which according to reports could arrive later this week, will address this latest glitch also.