Q: One update regularly fails to install on my Windows 7 PC. It’s called “Microsoft .Net Framework 4 Client Profile,” and when it won’t install I get the error code 643. Is this an important update, and, if so, is there a way to make it work?

— Ron Bender, Richfield, Minn.

A: That update is particularly troublesome on Windows 7 PCs, but it is important and there’s a way to make it install.

Many Windows programs developed by small companies rely on Microsoft’s “.Net Framework” to help them access databases and use the internet; without it they might not work. In your case, the existing “.Net Framework” software on your PC is probably corrupted, which prevents it from being updated.

To fix that, uninstall the program by going to Control Panel, clicking Programs and then clicking Programs and Features. In the resulting list, find Microsoft .Net Framework 4 Client Profile, right click it once and choose “uninstall.” Restart your PC and try installing the update again.

If that doesn’t solve the problem, check out other possible causes of error code 643, including software conflicts and malware infections (see tinyurl.com/yd7dc84z).

Q: How do I get rid of the pop-up error message that says “Your iCloud settings are out of date”?

— Russ Sklenicka, Lakeland, Fla.

A: The error code appears on Windows PCs that have the “iCloud for Windows” software, but haven’t been set up to use iCloud’s “two-factor authentication,” a double-password system that Apple now requires for added security.

Two-factor authentication requires a one-time setup in which a particular computing device — anything from and iPhone to a PC — is listed with Apple as “trusted.”

On Apple devices, each trusted device is given a verification code which, together with an Apple password, allows it to access any part of iCloud. On a Windows PC, the computer is given an “application-specific password” that allows a particular Windows program to access iCloud. For example, it would allow Windows 10 Mail or Microsoft Outlook to display iCloud e-mail.

To set up two-factor authentication, see tinyurl.com/yd936u86 for a Windows PC or tinyurl.com/z5jpvyq for an iPhone, iPad or Mac.

Q: I can’t figure out what’s taking up all the memory on my phone. I have only 100 photos, I haven’t installed extra apps and I clear the cache (temporary) memory all the time.

Because of this problem, I’m now on my third phone, a Samsung with 16-gigabytes of internal memory. I previously had Huawei and ZTE phones, both with 8-gigabyte memories that quickly filled up. What can I do?

— Margaret Keymes, Minneapolis

A: There's a better way free up storage space on phones with limited internal flash memory: Install an SD memory card on the phone, then transfer photos and other data to the card. (For details about SD cards, see tinyurl.com/ycslu97w). For SD card use, check your owner's manual or see tinyurl.com/ybdkrurb for Huawei, tinyurl.com/ya8uodtp for ZTE and tinyurl.com/y7b5rcuf for Samsung.

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ABOUT THE WRITER

Steve Alexander covers technology for the Minneapolis Star Tribune. Readers may write to him at Tech Q&A, 425 Portland Ave. S., Minneapolis, Minn. 55488-0002; email: steve.j.alexander@gmail.com. Please include a full name, city and phone number.