Has already been made available to users and it can be exciting to get your hands on a new operating system loaded with new features and enhancements. While most users are having a smooth experience with the latest operating system, some have been facing annoying issues. In this post, we will go through the 10 common problems of macOS Sierra and how to fix them. 10 Most Common macOS Sierra Problems and How to Fix Them #1. MacOS Sierra Upgrade Shows “An Error Has Occurred” Or “Failed to Download” This is a common issue that many users face while upgrading their Mac to a new operating system. The solution is quite straightforward and easy to tackle.

To fix this issue, you have to delete the existing macOS Sierra installer and re-download it. To do so, open Launchpad and you should see the half-downloaded “Install macOS Sierra” file with a question mark on it. Delete this file, reboot your Mac and retry the download process. Mac App Store Shows macOS Sierra as “Downloaded” If you go to the Mac app Store and see that macOS Sierra is shown as “Downloaded”, then it means that you either have installed the beta version or the GM build.

To be able to download the final version of macOS Sierra, you have to remove any existing “Install macOS Sierra” installer files from your Mac or from a connected hard drive. Once you’ve removed the installer files, go back to the Mac App Store and you should be able to install the final version. “This copy of the Install macOS Sierra.app application is damaged, and can’t be used to install macOS” Error If you see this error while attempting to download and install macOS Sierra, it means that the file is either corrupted or was interrupted during download.

One way to fix it is to delete the “Install macOS Sierra” file from Launchpad, reboot your Mac and download the macOS Sierra file again. Wi-Fi Problems Internet connection and Wi-Fi problems are the most annoying issues anyone could face while using a new operating system. Some users have reported that webpages, including downloads, load very slowly after upgrading to macOS Sierra. Firstly, you have to ensure that there are no issues with your router and that your ISP is providing a proper internet connection.

If these two have no issues then you can try deleting your WiFi preferences and start afresh. To do so, read the steps below:. On your Mac, open Finder. Select Go from the top menu and choose Library (you have to press the Alt key while the menu is open so that you can view the Library option). Go to /Preferences/SystemConfiguration/.

Delete the following files:. com.apple.airport.preferences.plist. com.apple.network.identification.plist. com.apple.wifi.message-tracer.plist. NetworkInterfaces.plist. preferences.plist. Next, reboot your Mac and router.

MacOS Sierra Installation Freezes or Crashes If your Mac freezes while installing macOS Sierra or the installation crashes, then there are a few methods to fix this annoying problem. The first thing to do is to disable or uninstall any Antivirus software that is present on your Mac, as they may interfere with the installation. Ensure that you have a proper and reliable internet connection.

Next, you can try installing macOS Sierra in Safe mode. To do so, switch off your Mac by holding the Power button until it shuts down. Next, turn it on and when you hear the startup sound, hold down the Shift key. When the Apple logo appears, release the Shift key and your Mac should now be in Safe mode. Now proceed with installing macOS Sierra. Not Enough Space to Install It can be annoying if your macOS Sierra installation is interrupted just because you don’t have enough space to install the new operating system. You have to make sure that you have at least 8GB of free space available on your Mac. So get rid of all the junk files and delete unnecessary files and apps.

Check out our articles on how to free up more storage space on your Mac. If the error still appears after clearing up some space, then try installing macOS Sierra in Safe mode. Next, you can try installing macOS Sierra in Safe mode. To do so, switch off your Mac by holding the Power button until it shuts down. Next, turn it on and when you hear the startup sound, hold down the Shift key. When the Apple logo appears, release the Shift key and your Mac should now be in Safe mode. Now proceed with installing macOS Sierra. Lag & Other Issues with Logitech Mouse Unfortunately for users of some Logitech-branded mice, the update to macOS Sierra, and has caused a series of issues in their accessories.

Some of those problems include “laggy” response times, and some customizable buttons flat-out not responding at all. The issue stems from a lack of compatibility between macOS Sierra and Logitech’s Control Center app. The latest release for the Control Center app, version 3.9.4, specifically mentions that the M705’s forward and back buttons are not working, and scrolling was “problematic” as well. Therefore, you have to wait until Logitech releases an update to fix the issue. Mac Won’t Turn on after Installing macOS Sierra If you’ve installed macOS Sierra, but your Mac isn’t starting, you can try resetting the NVRAM and PRAM. To do so, restart your Mac and then hold down the Cmd + Option + P + R keys together until you hear the startup chime sound twice. After the second chime sound, release the keys and your Mac should hopefullly boot up without any issues.

Installed Apps Show ‘Damaged and Can’t Be Opened’ Error If you have updated to macOS Sierra and get a ‘Damaged and can’t be opened’ error when trying to launch an app, you should make sure that the app has been updated to the latest version. If the issue still persists after updating the app to the latest version, remove it from your Mac and install it again. As a last resort, if nothing else works, you can clear the cache. Open Finder.

Click ‘Go’ from the top menu and choose ‘Go to Folder’. Enter /Library/Caches into the text box.

Delete the files from every folder. Now, repeat the same process for /Library/Caches (without the symbol) Reset the PRAM by restarting your Mac and holding down Cmd + Option + P + R keys. Even after all this, if the problem still persists, then try launching the faulty app while holding Cmd + Option keys.

Fixed Usage Of Sigaction. Previous Way Did Not Work For Mac Pro

These are some of the most common issues that users are facing after upgrading their Mac to macOS Sierra. For most, it has been a seamless experience and we hope that this article will clear out all the issues you’re facing with the new operating system. What problem are you facing with macOS Sierra?

Let us know in the comments below. ICloud Error and Authentication Issues Some features and functionality of macOS Sierra depend on iCloud and you’ll be asked during the setup process to enable some of these features such as Storage Optimization and iCloud Documents and Desktop. You can skip them if you want but an annoying issue that some users are facing is that iCloud constantly pops up for authentication or displays an error. For instance, you may get an ‘Error connecting to iCloud’ popup or see something like ‘This Mac can’t connect to iCloud because of a problem with ’.

To fix these issues, do the following steps:. Open the  Apple menu and choose System Preferences. Select iCloud and click on ‘Sign Out’. Next, reboot your Mac and open the iCloud preference pane again.

Sign in into your iCloud account. Feel your Mac has become Slower? If you feel that your Mac has become slower after upgrading to macOS, then check out our articles to speed up your Mac.

Have you hit any of these issues while upgrading to macOS Sierra? Please share your experience in the comments below.

Process Control and Signals, Projects 6 and 7 This sequence of two projects shows how to create and test (6) a child process and signal handlers, and (7) a simple command interpreter, or shell. The first project asks you to manage (in a simple way) the coordination between two processes. The second project extends the first with interactive features and multiple processes. The first project is individual and will take one week, while the second is for two people and will take two weeks. We will use the description of Project 6 for the in-class discussion of Process Control and Signals on Mar.

13, 15 and 18; Project 6 is then due before class on Mar. Note that the second midterm exam will be given during the time you are working on Project 7, and a solution to Project 6 will be posted before the in-class exam review on Mar. 27., with a complete example program, is provided. You should work through the background information first; we covered some of this in class on Feb. A starting point for Project 6 is also provided here, which uses some of the background information.

A solution to Project 6 will be posted soon after the due date, so that you can check your work, review for the exam, and proceed to the next project even if not completely successful. Please be sure to turn in your work before the solution is posted, even if it is incomplete.

Late submissions will not be accepted. Here is what you should turn in for these projects:.

a printed copy of the source code, with comments, your name, and the date;. a printed copy of the output from the program (if it compiles and runs successfully);. a printed copy of the error messages from the compiler or runtime system (otherwise);. any additional write-up required for the project;. a brief statement of how you allocated your time working on the project (planning, reading the manuals, coding, debugging, cursing the prof, etc.).

An electronic version of your program should be submitted through ANGEL. Specific instructions will be included with each project. Be sure to attach all parts of your program's source code.

Do not attach an executable file. The dropbox will remain open until 2 pm on the project due date for Project 6, and 11 pm for Project 7. You can run your examples on Solaris, Linux or Mac OS X, but please specify which system you used, and when. The test cases to demonstrate the output are your choice; 5 or 6 should be enough.

There are some examples at the end of this description. The time allocation statement should be like '1 hr planning.' , and not like '1% planning.' ; there's no reason to be completely precise about it, but at least try to be honest.

The notation indicates a place in the description where you should have a version of the program that compiles correctly without complaint, and does some limited action correctly. You may need to rewrite code between the checkpoints. Only the final version needs to be turned in.

Code that was provided and remains unchanged does not need to be turned in, but you should indicate this somewhere. Some parts of the project descriptions review topics discussed earlier in the course, when they might not have seemed so important, and in case they didn't sink in the first time. CMPSC 311, Project 6 Posted Mar. Due Friday, Mar.

22, 2013, 2 pm (electronic version, to ANGEL), and in class (paper version). A solution will be posted on ANGEL at 2 pm on Mar.

22, so no late projects will be accepted after that time. As a result of cancelling class on Mar. 18, the due date is changed to Monday, Mar. 25, same times. Reading (review). CS:APP, Sec.

1.7.1, Processes; Sec. 1.9.1, Concurrency and Parallelism; Ch. 702-703); Sec. 8.1, Exceptions (concentrate on interrupts and system calls); Sec. 8.3, System Call Error Handling; Ch. 12 intro (pp.

934-935, Concurrency). APUE, Sec. 1.6, Programs and Processes; Sec. 1.7, Error Handling; Sec. 1.9, Signals; Sec. 7.3, Process Termination.

lecture notes Reading (new, processes). CS:APP, Sec. 7.9, Loading Executable Object Files (for exit); Sec.

8.2, Processes; Sec. 8.4, Process Control (skip Sec. 8.4.6 for now - we'll come back to it later). APUE, Sec. 8.1, Process Control, Introduction; Sec.

8.2, Process Identifiers; Sec. 8.3, fork Function; Sec.

8.5, exit Functions; Sec. 8.6, wait and waitpid Functions Reading (new, signals). CP:AMA, Sec. 24.3, Signal Handling ( signal and raise). CS:APP, p.

50 (signals can be enabled/disabled); Sec. 8.5, Signals (this goes into more detail than is covered here, but we'll come back to it all later). APUE, Sec. 10.1, Signals, Introduction; Sec. 10.2, Signal Concepts; Sec.

10.3, signal Function; Sec. 10.8, Reliable-Signal Terminology and Semantics; Sec. 10.9, kill and raise Functions; Sec. 10.10, alarm and pause Functions (p. 313 is the important part); Sec. 10.14, sigaction Function (we'll give you a particular call for this project); Sec. 10.19, sleep Function; Sec.

10.22, Summary Reading (new, further concepts). CS:APP, Sec. 9.8.2, Fork, Revisited; Sec. 12.7.2, 12.7.3, Reentrancy; Sec. 12.7.4, Races. 10.4, Unreliable Signals; Sec.

10.5, Interrupted System Calls; Sec. 10.6, Reentrant Functions That's a lot of reading. The rest of this project description provides a quick introduction to these topics, hopefully enough to get you through the project.

All of this material will be needed for Project 7. This snippet from APUE p. 289 is a useful mantra: 'It is often important to understand what is wrong with an implementation before seeing how to do things correctly.' . Note that many of the problem areas associated with processes and signals have to do with the relative timing of events, and that may be hard to reproduce when testing a program.

This project is designed to have certain events occur at expected times, but there is still some variability possible. The project description and 'starter kit' are written as if you are using Solaris. When there are significant differences between Solaris, Linux or Mac OS X, we will describe them, but it's possible that we didn't catch all the differences. It's expected that Linux or Mac OS X will be your first choice for development, but some of the points we want to make are easier to see with Solaris.

For a preview of Project 7, see CS:APP Homework Problem 8.26, pp. The objective of the project is to learn about processes and signals. Over half the code is provided directly from this description. Some of the code is directly useful, and some of it consists of examples that are intended to be discarded or replaced after you understand how the example works.

Be sure to use the compiler commands ' c99 -v.' Or ' gcc -std=c99 -Wall -Wextra.' , and to recompile the program often as you work on it. The -h option with pr6 should print (at least) Usage: pr6 -h -v -a n -b n -c n -f n -s n -t n -x n The options should work as follows: -h print a help message -v enable verbose mode (extra output) -a n child alarm time interval, default 0 -b n parent alarm time interval, default 0 The alarms repeat at regular intervals. The default value 0 means that the alarm feature is not to be used.c n fork n child processes, default 0 You can force a maximum value for n, but the program should at least allow n between 0 and 8.f n fflush before fork, 0 = no, 1 = yes, default 1 This is described later. It is an 'extra feature' that allows some experimentation.s n child sleep time, default 0 -t n parent sleep time, default 0 The default value 0 means that the process does not sleep.x n child exit status n, default 0 The default value is EXITSUCCESS, which is 0. The options -a, -s and - x apply to each child process.

The option -v applies to the parent and child processes. The remaining options apply only to the parent process. The starting point of the project is in the file, which you should save and test. Compile it with one of these commands, using the Sun or GNU compilers, and C89 or C99. The -D option with C99 clears up a warning from the compilers on Solaris about getopt.

Cc -v -o pr6 pr6.1.c gcc -Wall -Wextra -o pr6 pr6.1.c c99 -v -DPOSIXCSOURCE=200112L -o pr6 pr6.1.c gcc -std=c99 -Wall -Wextra -DPOSIXCSOURCE=200112L -o pr6 pr6.1.c With Linux, you can use instead -DPOSIXCSOURCE=200809L. With Mac OS X, just omit it. There will be more code provided later in the project description. The idea of this project is to generate several processes, which will all send output to the same place, the terminal or a file.

We need to start with a simple mechanism to help identify which process has printed a message, and when. The initial testing will be with signal handlers for only one process. You should now pick up and read the code in. Note that the file names have an embedded underscore not a space; web browsers that underline links make this difficult to see. The functions defined here are char. Ctime(char buf26); void printmsg(char.msg); void printmsg1(char.msg, int n); void printmsg2(char.msg, int n1, int n2); void printmsgerror(char.msg, char.errmsg); void printmsgabort(char.msg); Here is an example of using the printmsg function, printmsg('Hello, world'); 18173: Tue Mar 12 13: Hello, world If the child process and the parent process want to print the same text, printmsg makes it possible to see which process caused the output, and at what time.

If more than two processes are involved, then having the process ID and time attached to an error message or diagnostic output makes it easier to see what's going on. Note that printed output is typically buffered, and you might see an earlier message from one process appear after a later message from a different process. This can be disconcerting, but it isn't wrong. If you sort the output by process number, or by the time, then everything looks right. These functions are built using ctime(3C) and getpid(2). Getpid(2) returns the process identifier of the current process.

Getppid(2) returns the parent process's identifier. The type of a process identifier is pidt, an integer type defined in the header. The ps(1) command can be used to see the identifiers of all processes currently running, but that's the wrong way to obtain process numbers for use in a program. It might be a good idea to run ps occasionally (or top continuously) if you think your program has a bug, to be sure you are not accumulating a large number of processes.

Later, when studying thread programming, we will need the reentrant function Ctime. It is useful here because it allows a simple method of giving a time-stamp to a line of output. You should understand why ctime(3C) is not reentrant, and why ctimer(3C) is necessary.

It will be harder to understand why there are two versions of ctimer. (It's because Sun implemented one proposed version before a second version was chosen by the POSIX committee to be the standard version. The old version remains so that old code doesn't need to be rewritten. No one ever said this business of programming makes complete sense. More information can be found in /usr/include/time.h, but it's not easy reading and not really recommended at this point.) The lines #ifdef. #endif are used by the C preprocessor to select which part of the code is actually given to the compiler. If you want to test both versions in pr6ctime.c, the Sun compiler command now is one of.

Tar cvf project-6- username.tar pr6.5.c pr6ctime.ch pr6signal.ch pr6wait.ch pr6table.ch Makefile tar tvf project-6- username.tar gzip project-6- username.tar ls -l project-6- username.tar.gz Login to ANGEL and put the file project-6- username.tar.gz in the ANGEL Dropbox for Project 6 (with your username substituted, of course). The grade will be based on the paper version that you turn in at class time, and the electronic version is in case we have any questions about your program or data.

Here are some remarks by a former student, about his experience dealing with fork. There's a lot of belated wisdom here. I spent a loonnggggggggg time trying to figure out simply what was going on. Fork made little sense to me initially but I looked up examples online but mainly learned by making simple test programs. To me it wasn't clear that fork split the program at the line of fork. I was under the initial impression that fork started a process from the beginning.

This was followed/coincided with a period of intense cursing. There wasn't much planning.

Once I figured out what to do, things fell into place. Last revised 12 Mar.