I recently started using Linux Ubuntu (18.04.1). After recent update I restarted my laptop to switch for Windows. The next day when I tried to launch Ubuntu, instead regular purple dual boot menu I got this:  Unexpected return from initial read: Volume Corrupt, buffersize 1000 Failed to load image \EFI\ubuntu\grubx64.efi: Volume Corrupt start_image() returned Volume Corrupt System BootOrder not found.              Initializing defaults Failed to open \EFI\ubuntu\grubx64.efi\ - Volume Corrupt Failed to load image \EFI\ubuntu\grubx64.efi: Volume Corrupt start_image() returned Volume Corrupt StartImage failed: 10   And no button works. The main reason I ran here to start this thread is because I can not access Ubuntu recovery mode by any possible way. I know this part: Failed to open \EFI\ubuntu\grubx64.efi\ maybe related to various reasons so it is hard for me to find precise solution. Please, could anyone provide some newbie-friendly quick guide how to solve this issue... Provided there is one that does no include reinstalling OS.
Today after I installed Ubuntu 16.04 via USB on my pre-installed Windows 8 machine, I was required to restart my computer. After doing so I wasn't offered to select an OS, so after searching the internet, I came across Boot-Repair which I ran using the Try Ubuntu option in my Ubuntu installation USB. Following the boot repair I got a message saying,  If your computer directly reboots into Windows, try to change the boot order in your BIOS. If your BIOS does not allow to change the boot order, change the default boot entry of your Windows bootloader. For example, you can boot into Windows then type the following in an admin command prompt: bcdedit /set {bootmgr} path \EFI\ubuntu\shimx64.efi   After I rebooted my PC, I am receiving the following error message for about 3 seconds, after which it boots automatically into Windows 8, without letting me access Ubuntu. Error received while booting after manufacturer's logo, before grub: Failed to open \EFI\BOOT\grubx64.efi - Not Found   Failed to load image \EFI\BOOT\grubx64.efi: Not Found     start_image() returned Not Found    So I tried the other solution of typing that command in the cmd, to which my surprise, worked, and I am now prompted a window (grub) to choose my OS each time I turn on my PC, but unfortunately, I still receive an error each time, that lasts about 3s, after which I can choose my OS (both are working just fine) and work normally. Do you have any suggestions to get rid of the error message each time I boot my PC?
Number of non-isomorphic groups of order 21 At what stage should acknowledgements be inserted into the paper if review is not double-blind? When the review process is double-blind, I guess (although I have not read this anywhere) that acknowledgements should not be written in the submitted paper, as this might break anonimity. They should only be inserted into the camera-ready version, after the paper is accepted.  What is the custom when the review process is not double-blind? Should I write the acknowledgements in the submitted version, or wait to the camera-ready version? Sunlight Sensitivity looks pretty bad — Disadvantage to attack rolls and Perception checks whenever you, your target, or what you're trying to perceive are in direct sunlight. I hope I'm missing something, since no other PC race has a comparable hindrance.  Are there any ways you have used to mitigate this flaw to make players of this race not at a severe disadvantage (or, if it doesn't need mitigation, explain why it's already balanced without any action required)? How can I access the apache basic-auth username in a PHP script? What invisible flicker do different types of light bulbs have? What waveform does the light coming off different types of artificial light sources have and (of course) what are the underlying physical reason for them?    I was inspired to ask this question because of several things I have been hearing lately.  Firstly, there was a recent TED talk about how .  Researchers have been working on the problem for a little while now and they've made a fairly impressive product, but it was only recently made possible by the LED technology, which has such a fast response that it can easily compare to the transfer rates of electric information condiuits that we normally use.  My understanding is that incandescent bulbs flicker because they have 60 Hz AC power being pulsed through them.  In fact, I think 60 Hz was chosen in the first place because it was a threshold that was unnoticeable to humans.  Looking at a  demonstrates that it has a very significant lag time responding to both the normal electrical phasor and being turned off.  In other words, it flickers but it doesn't go dark at any point in the AC waveform.  Looking for more information, however, I was a little disappointed, since nothing seemed to give a graph of lumens emitted over time for all different kinds of bulbs.  Of course, there isn't just one relevant time scale.  A light could flicker with 60 Hz and also flicker with 2000 Hz (I just made that up).  I'm interested in the complete picture of what lights exhibit what patterns. What are the consequences of using a low-wattage USB-C power supply with a MacBook Pro? Is it possible to view Google Chrome bookmarks and history from the terminal Is it possible to view Google Chrome bookmarks and history by using command line? Is there a way to easily turn on/off showing the boot messages (loading the services) when Ubuntu starts? Is it something in Grub2?  I am running 10.04. Find the smallest disk in complex plane containing the eigenvalues of a matrix (NBHM 2012) Consider the given matrix  $$\left[\begin{matrix}1&amp; -2&amp; 3&amp; -2 \\1&amp; 1&amp; 0&amp; 3\\-1&amp; 1&amp; 1&amp; -1\\0&amp; -3&amp; 1&amp; 1&amp;\end{matrix}\right]$$  Find out the smallest disk like ($|z-1| &lt; r$ ) in the complex plane containing the eigenvalues of the given matrix.  One easiest method is to find out the eigenvalues from the characteristic equation of the matrix. I can do it so no problem with it.   I am looking for a method to solve the problem without the above method that can be evaluated in very short time. This type of method is possible, I believe.  Thank you for your help Prove that $\binom{m+n}{m}=\sum\limits_{i=0}^m \binom{m}{i}\binom{n}{i}$ I need to proof this following equality :  $$\binom{m+n}{m}=\sum_{i=0}^m \left(\binom{m}{i}\binom{n}{i}\right)$$  This is what I did combinatoric proof:  Left : subset with $m$ members from $m+n$  Right : $\binom{m}{i} \rightarrow$ The number of subsets in set $m$ could also be written as $2^m$ AND $\binom{n}{i} \rightarrow$ the number of subsets with $m$ members from set $n$  In case $ n \leq m \implies \binom{n}{i}=2^n$  So this is what I came up with I still can't see why those expression are equal.  Any ideas? Thanks. How do you factorise $x^3z - x^3y - y^3z + yz^3 + xy^3 - xz^3$? I'm trying to factorise $$ x^3z - x^3y - y^3z + yz^3 + xy^3 - xz^3 $$ into four linear factors.  By plugging it into WolframAlpha I've learned that it's $$-(x-y)(x-z)(y-z)(x+y+z)$$  My question is: what are the steps involved in factorising the expression? Is there a method I don't know about that I'd have access to with my limited maths?  Really appreciate any help! Why are there no Pokémon near me? I see pictures online of everyone having all these Pokémon to catch being everywhere around them, but it seems like I can only ever see one or two. I live in a rural area, but even walking miles through the farmland, it's rare to find any Pokémon.  Why is this? How can I find more Pokémon? iPhone 6s with iOS 12.4 not connecting to MacBook Pro mid2015 with macOS 10.14.6 Below you find the design for our business cards. The triangles are yellow, as you can see outside of the canvas. However, inside the canvas, only when I set the Color Mode to CMYK, they appear pink. When I switch the Color Mode back to RGB, they appear yellow as expected. However, when I print them, in both cases they turn out pink...   I would just like to know what is going on here and how I can change them back to the right colors?  CMYK Colors: How is the authenticity of Debian packages guaranteed? I'm looking for a good algorithms for the following problem: Given a 3D grid of voxels (which may be either empty or filled), if I pick two non-adjacent voxels, I want to know if they are connected to each other by other voxels.  For example (to illustrate the situation in 2D), where # is a filled square:    1 2 3 a # # # b # # c # # #   If I pick a3 and c3, I want to determine as quickly as possible if they they are connected; if there is a path between a3 and c3 through filled pixels. (The real situation is in a 3D voxel grid, of course.)  I've looked at floodfill algorithms and path finding algorithms, but I'm not sure which to choose. Both do unneccesary work: Flood fill tries to fill all voxels, but this is not needed. Path-finding algorithms are usually concerned with finding the shortest path, which is also not necessary. I only need to know if there is a path.  What algorithm should I be using?  Edit: based on the comments, I think should add the following: the content of the voxels are not known in advance, and also, the algorithm is needed to detect if removal (emptying) of a voxel would cause the group of voxels to break into two or more smaller groups. Why are all snaps being mounted and listed as block devices or partitions for Ubuntu 18.04? can anyone help me with this, I got stuck on it.  let $a_n$ and $b_n$ (for $n$ a non-negative integer) be two sequences of real numbers such that $\lim_{n\to \infty}a_n=a$ and $\lim_{n\to \infty}b_n=b$. prove that $\lim_{n\to \infty} \frac{a_0b_n+a_1b_{n-1}+....+a_nb_0}{n}=ab$. Do shots fired before the match starts count towards your end-of-game statistics? In Overwatch, there is short countdown for a few minutes before the match begins. During this time, the defending team is allowed to roam the map to set up their defenses, while the attacking team sits in a small lobby until the game starts and the doors open. (Or in KotH-type maps, both teams wait in a lobby.)  While players wait, it's not uncommon for them to fire off random shots, especially since a lot of the environment is destructable (it's entertaining to watch plush onions sail through the air in the arcade).   Do shots fired before the match starts count towards accuracy statistics at the end of the game? Often in fantasies involving magic casting spells requires a certain physical or mental toll on the caster. I don't recall any mention of spells being physically or mentally taxing in the Harry Potter universe.  Does this mean they can cast an unlimited number of spells in a given day without any negative effect to themselves?