Any good website or book for iOS troubleshooting? [on hold]

I’m a repair technician still learning iOS.

I know this question may seem improper, but I’m so fed up with having to research and test myself iOS to learn how it works that here it goes:

I’d be immensely grateful if anyone suggested to me a good book or website explaining iOS for technicians, illuminating on the secrets such as how to fix software or hardware issues of any kind a customer-facing technician may need. Something not to advanced please, I’m a just a repair tech not a developer.

Any help much welcome

Repeated Installation Failure on 19.04 and 18.04.2 – Troubleshooting advice?

For the first time in several years of using Ubuntu I’m completely failing to install on a couple of desktop PCs. They have identical specs, and both fail in similar ways so its highly unlikely its hardware failure. I’ve tried 19.04 and 18.04.2 LTS.

The installer fails on both from Live USB boot and from direct install. It fails due to random parts crashing at any point during the installer – the timezone picker crashes, the part which is making partitions fails, it fails with a random unknown error later in the process and tries to make an error report but crashes out completely during that phase. I can’t get any debugging information out.

I’ve tried disabling UEFI Secure Boot from BIOS and have gone through looking for any weird looking power savingfeatures in BIOS but I’m not really sure I’m looking for? I’ve formatted the disks with long format i.e. writing 0s just to make sure no weird partition problems from all the failed install attempts.

I’ve also tried two different USB sticks.

Any advice for where to look for errors or what to try switching off? Here is the hardware spec. Again I have two identical PCs both with this issue.

Processor (CPU) Intel® CoreTM i5 Six Core Processor i5-8500 (3.0GHz) 9MB Cache

Motherboard ASUS® H310M-A R2.0: Micro-ATX, DDR4, LGA1151, USB 3.1, SATA 6GBs

Memory (RAM) 16GB Corsair VENGEANCE DDR4 2400MHz

Graphics Card 2GB NVIDIA GEFORCE GT 1030

Troubleshooting X11 Forwarding after an SSH tunnel to an EC2 Instance

I am doing an SSH tunnel to an EC2 instance with the eventual goal of getting a working GUI of Stata.

I’ve done the SSH connection both through PuTTY and through just my CLI (Git Bash).

When I run xstata through my CLI I get an error message to define the Unix environment variable DISPLAY. I fix this error message by doing

export DISPLAY='IP:0.0' 

where IP is the IP address of my local computer.

Then, when I run xstata, nothing pops up and nothing is returned in my CLI. I get the same result after doing the SSH tunnel through PuTTY. With PuTTY, I set the display location to be localhost:0 (shown in the screenshot below). The screenshot below shows my PuTTY X11 Forwarding configuration.

PuTTY Configuration

I do have Xming and XLaunch installed on my local computer.

Any suggestions? I think the display location I am providing may be incorrect. All the different configurations I have tried based off docs and also feedback from others on the internet, such as localhost:0, IP:0, etc have not worked.

Troubleshooting 500 Internal Server Errors on IIS 8.5?

How does one tell the difference between an HTTP / HTTPS request that is failing in an ASP .NET Core application, and one that’s failing from an IIS mis-configuration?

Most of the time IIS and the ASP .NET Core have different logs, and the solution is often just to turn off HTTPS to figure out which is returning the error, but the error messages from IIS just seem to be along the lines of HTTP 500 Internal Server Error in the output of a W3C formatted log message, and they don’t specify anything deeper than that.

As far as I can tell, ASP .NET Core applications just sit behind IIS and requests/responses are kind of reverse proxied to the actual application.

I came across the following IIS configuration setting in which you can enable the tracing of failed requests, and it seems to specify that it will gladly log the deeper error messages as HTTP 500 Internal Server Error is mentioned at the bottom of that documentation, but I’m uncertain of this.

In-depth php script troubleshooting

Pardon, but I’m a bit of a programming noob.

I tweak my php script, then upload it to the web, then try testing it.

I include in my script a fopen command to open a log file, then I use a smattering of fwrite commands to check the contents of some variables after the script has run.

Is there a single command I can use in my script that will provide a comprehensive insight as to what my script is doing? I’m getting tired of writing dozens of fwrite’s… there’s got to be an easier way!


I need help troubleshooting my code for MergeSort and Merge

So I’ve been working on MergeSort for an Algorithm project, but I’ve ran into various problems when it comes to getting the code to sort the arrays. Whenever I generate a string and put it into MergeSort, it seems to just come out exactly the same. I want some help in finding where the mistake in my code is, why is it giving me this, and a solution with a simple, but good explanation.

Here’s what I’ve tried in the past: 1. I’ve tried to use return arr[0] instead of arr, but it throws me an error with it being unable to convert from int to int[]. 2. I’ve looked in my merge class and everything seems to be ok there. 3. I’ve discussed the issue with my teacher and he says that everything looks fine, but I know that there must be something wrong somewhere. 4. I’ve tried to remove return merge(arr1, arr2) but the system throws an error telling me I have to return something. 5. I’ve tried to print out the arrays individually, but it still shows no changes and is the exact same as the original string.

Merge Class:

private static int[] merge(int[] a, int[] b) {     int[] c = new int[a.length + b.length];     int counterA = 0;     int counterB = 0;     int counterC = 0;      while(counterA != a.length && counterB != b.length)     {       if(a[counterA] < b[counterB])       {         c[counterC] = a[counterA];         counterA++;         counterC++;       }        else       {         c[counterC] = b[counterB];         counterB++;         counterC++;       }     }      while(counterB == b.length && counterA != a.length)     {       c[counterC] = a[counterA];       counterA++;       counterC++;     }      while(counterA == a.length && counterB != b.length)     {       c[counterC] = b[counterB];       counterB++;       counterC++;     }      return c; } 

MergeSort Class:

public static int[] mergeSort(int[] arr) {      if(arr.length == 1)     {       return arr[0];     }      int[] arr1 = new int[arr.length / 2];     int[] arr2 = new int[arr.length - arr1.length];      for(int i = 0; i < arr1.length; i++)     {       arr1[i] = arr[i];     }      for(int i = 0; i < arr2.length; i++)     {       arr2[i] = arr[i + arr1.length];     }      arr1 = mergeSort(arr1);     arr2 = mergeSort(arr2);      return merge(arr1, arr2); } 

Because the array is randomly generated, an example would be this: 9, 1, 7, 5, 7, 2, 2, 9, 8, 9

The intended result should be this: 1, 2, 2, 5, 7, 7, 8, 9, 9, 9

However, this is what the output is instead: 9, 1, 7, 5, 7, 2, 2, 9, 8, 9 (The array comes out unchanged)

Pfsense OpenVPN Troubleshooting

I’m trying to setup a Pfsense OpenVPN tunnel and am running into issues. I’ve set these up several times without issue but this environment has unique constraints.

Currently I connect to the firewall and get an IP but am unable to ping across the tunnel. (Firewall rules are in place – here).

dev tun persist-tun persist-key cipher AES-128-CBC (HAVE TRIED WITH MULTIPLE CIPHERS) auth SHA256 tls-client client resolv-retry infinite remote XX.XX.XX.XX 1194 udp lport 0 verify-x509-name "Open-VPN-ServerCert" name auth-user-pass remote-cert-tls server 

The modem has 5 static IP’s and the OpenVPN will be running on one static IP, however, there is an existing Ubiquiti firewall running a l2tp VPN on another of the static IP’s. Is this a viable scenarios’s or will it interfere with Open-Vpn tunnel ? Do I need to to add sometime of special rule for routing or nat ?

“pkexec xfce4-terminal” has stopped working – help with troubleshooting, please

I have been using an upgraded xubuntu machine (16.04 to 18.04) for just under a year now. I use a root terminal extensively, so on about the 2nd day after my upgrade I figured out how to get it working with pkexec instead of gksu.

Today it stopped working, with no action on my part, and no updates applied. Rebooting had no effect.

Where do I start to troubleshoot this?

Here’s my /usr/share/polkit-1/actions/xfce4-terminal.policy file:

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE policyconfig PUBLIC "-//freedesktop//DTD PolicyKit Policy Configuration 1.0//EN" ""> <policyconfig> <vendor>xfce4-terminal</vendor> <vendor_url>xfce4-terminal</vendor_url> <icon_name>terminal</icon_name> <action id="org.freedesktop.policykit.pkexec.xfce4-terminal"> <description>Run "xfce4-terminal"</description> <message>Authentication is required to run xfce4-terminal</message> <defaults> <allow_any>auth_admin</allow_any> <allow_inactive>auth_admin</allow_inactive> <allow_active>auth_admin</allow_active> </defaults> <annotate key="org.freedesktop.policykit.exec.path">/usr/bin/xfce4-terminal</annotate> <annotate key="org.freedesktop.policykit.exec.allow_gui">true</annotate> </action>

auth.log is showing no error. here is an example — the first is launching gparted via pkexec. it works normally. The second is launching xfce4-terminal. xfce4- terminal never appeears.

Mar 22 22:31:05 ooboontwo pkexec: pam_unix(polkit-1:session): session opened for user root by (uid=1000) Mar 22 22:31:05 ooboontwo pkexec[17035]: derek: Executing command [USER=root] [TTY=unknown] [CWD=/0data/ssd0/home/derek] [COMMAND=/usr/sbin/gparted] Mar 22 22:31:18 ooboontwo pkexec: pam_unix(polkit-1:session): session opened for user root by (uid=1000) Mar 22 22:31:18 ooboontwo pkexec[17303]: derek: Executing command [USER=root] [TTY=unknown] [CWD=/0data/ssd0/home/derek] [COMMAND=/usr/bin/xfce4-terminal] Any help appreciated!

Troubleshooting Google reCaptcha v.3 > Why no stats, even though icon appears on form?

I’ve just installed (well, a PHP programmer did it for me) Google reCaptcha (v. 3, Invisible) on a form page. The page’s PHP code performs a sendmail and populates an external database upon submission. In recent years, the page has attracted bots and spammers, so a reCaptcha was called for.

The Dashboard page (at Google, where the reCaptcha is configured) doesn’t offer any tools for verification of the tool, and that seems like a shortcoming. In any case, it does have a link to download the Analytics. However, after a month of use, I’m still getting spammy submissions.

Most perplexing, though, is that the .CSV file I download has no records, only the column headings.

Part of my testing: I pulled the “security” settings (“Dashboard > Advanced”) all the way down, and this prompted a visual challenge. And the reCaptcha icon is displayed on the form page.

Can anyone suggest how I can effectively troubleshoot this? I can’t find anything in the Docs about how often the analytics gets refreshed, but, even on a day with a handful of submissions, it’s always empty.

Fuji X-T2 troubleshooting: On-camera flash fires only once

this is an issue that has only started showing up and seem to point towards something physically wrong with the camera/ hot shoe somehow. The problem is any flash that I mount on camera only fires on the first shot, and doesn’t on any shot after. Turning the camera off then on again between shots is the only solution to use a flash currently, and it’s obviously frustrating and not the most practical solution. Even then, the shot isn’t properly exposed either. Same exact problem with both the Godox tt685f and the EF-X8.

Camera is in manual shutter and not ES, single shot mode and not in continuous or BKT mode, does the same thing in both manual and TTL modes, fully charged batteries in camera and flash, cleaned connector pins on camera and flash, flash confirmation on the left side of screen is visible (flash icon is not crossed out) so the camera knows it has a flash mounted. I haven’t tried updating camera and flash firmware, in the case of the Godox. I also haven’t tried using the Godox off-camera with a trigger yet.

I was using these flashes earlier in the year no problem which is the main reason why this all confusing and seems to point towards something broken in the camera somehow. Seems like something is stopping them from firing after that first shot. Just want to see if anyone has experienced this issue before, and has possible fixes before thinking about getting camera repaired. Completely baffled what is going on.