After upgrading from Ubuntu 18 to 20.04.1 I can no longer read .epub books with Calibre. On opening a book.epub file, the book is opened for editing and I get an error message reading &quot;Failing to launch the worker process used for rendering the preview&quot;. The error details are: calibre, version 4.99.4 ERROR: Failed to launch worker: Failed to launch the worker process used for rendering the preview Traceback (most recent call last): File &quot;/usr/lib/calibre/calibre/gui2/tweak_book/preview.py&quot;, line 92, in run self.worker = offload_worker(priority='low') File &quot;/usr/lib/calibre/calibre/utils/ipc/simple_worker.py&quot;, line 260, in offload_worker listener, w = create_worker(env=env, priority=priority, cwd=cwd, func='offload') File &quot;/usr/lib/calibre/calibre/utils/ipc/simple_worker.py&quot;, line 130, in create_worker address, listener = create_listener(auth_key) File &quot;/usr/lib/calibre/calibre/utils/ipc/server.py&quot;, line 141, in create_listener l = LinuxListener(address=address, authkey=authkey, backlog=backlog) File &quot;/usr/lib/calibre/calibre/utils/ipc/server.py&quot;, line 110, in init self._listener._unlink.cancel() AttributeError: 'NoneType' object has no attribute 'cancel' I've tried reinstalling Calibre but that didn't help. Any suggestions? Thanks,
Calibre stopped working recently. Tried uninstalling and reinstalling. When I open a terminal and call $calibre I get the following error message: Traceback (most recent call last):   File &quot;/usr/bin/calibre&quot;, line 20, in &lt;module&gt;     sys.exit(calibre())   File &quot;/usr/lib/calibre/calibre/gui_launch.py&quot;, line 73, in calibre     main(args)   File &quot;/usr/lib/calibre/calibre/gui2/main.py&quot;, line 543, in main     listener = create_listener()   File &quot;/usr/lib/calibre/calibre/gui2/main.py&quot;, line 514, in create_listener     return Listener(address=gui_socket_address())   File &quot;/usr/lib/calibre/calibre/utils/ipc/server.py&quot;, line 110, in __init__     self._listener._unlink.cancel() AttributeError: 'NoneType' object has no attribute 'cancel'  Do I need to install some dependency that the sudo apt install didn't get? I tried installing via command line and the software installer/updater GUI. I'm on version Ubuntu 20.04.1 LTS. I made sure that my software in general is up to date also.
Multirow and Multicolumn with missing lines in QGis 1.8 were lots of predefined coordinate systems (national projections). Where have they all gone in qgis 2.0? I specifically need the Gauß-Krüger-Projections Zone 1 to 5.  Is there any plugin to load those coordinate systems? How to interpret these acf and pacf plots Following are acf and pacf plots of a monthly data series. The second plot is acf with ci.type='ma':    The persistence of high values in acf plot probably represent a long term positive trend. The question is if this represent seasonal variation?  I tried to see different sites on this topic but I am not sure if these plots show seasonality.           Edit: following is the graph for lag upto 60:     Following are plots of diff(my_series):     And upto lag 60:     Edit: This data is from:  Here the contributors did not consider acf and pacf plot of original or differenced series worth mentioning (so it must not be important). Only acf/pacf plots of residuals was referred to in a couple of places. Prove that $f$ is differentiable Maximum Likelihood Estimate with different parameters Shuffle an array with python, randomize array item order with python What's the easiest way to shuffle an array with python? iOS emails stuck in All Inboxes In the iOS Mail app, there are 4 emails in the "All Inboxes" section. Those 4 emails are NOT in the actual inbox on Gmail.  I thought, oh well I don't mind deleting them entirely since they're just newsletters. I deleted them directly on gmail, but they still appeared in iOS. So I tried deleting them via iOS and ... they keep coming back!  Even stranger, the 4 emails ONLY appear in "All Inboxes", they don't appear in any of the sub-account inboxes.  So, I disabled "Mail" in my gmail account. They're still here! I no longer have a "gmail" sub-account, but those 4 emails are still in All Inboxes. I tried to quit the app a few times, restart the phone. Still here...  When I tap on one of those messages, I get a black screen (dark mode), no errors. Applications Not Reopening After Restart Why don't languages raise errors on integer overflow by default? In several modern programming languages (including C++, Java, and C#), the language allows  to occur at runtime without raising any kind of error condition.  For example, consider this (contrived) C# method, which does not account for the possibility of overflow/underflow.  (For brevity, the method also doesn't handle the case where the specified list is a null reference.)    //Returns the sum of the values in the specified list. private static int sumList(List&lt;int&gt; list) {     int sum = 0;     foreach (int listItem in list)     {         sum += listItem;     }     return sum; }   If this method is called as follows:  List&lt;int&gt; list = new List&lt;int&gt;(); list.Add(2000000000); list.Add(2000000000); int sum = sumList(list);   An overflow will occur in the sumList() method (because the int type in C# is a 32-bit signed integer, and the sum of the values in the list exceeds the value of the maximum 32-bit signed integer). The sum variable will have a value of -294967296 (not a value of 4000000000); this most likely is not what the (hypothetical) developer of the sumList method intended.  Obviously, there are various techniques that can be used by developers to avoid the possibility of integer overflow, such as using a type like Java's , or the  keyword and  compiler switch in C#.  However, the question that I'm interested in is why these languages were designed to by default allow integer overflows to happen in the first place, instead of, for example, raising an exception when an operation is performed at runtime that would result in an overflow.  It seems like such behavior would help avoid bugs in cases where a developer neglects to account for the possibility of overflow when writing code that performs an arithmetic operation that could result in overflow.  (These languages could have included something like an "unchecked" keyword that could designate a block where integer overflow is permitted to occur without an exception being raised, in those cases where that behavior is explicitly intended by the developer; C# actually .)  Does the answer simply boil down to performance -- the language designers didn't want their respective languages to default to having "slow" arithmetic integer operations where the runtime would need to do extra work to check whether an overflow occurred, on every applicable arithmetic operation -- and this performance consideration outweighed the value of avoiding "silent" failures in the case that an inadvertent overflow occurs?  Are there other reasons for this language design decision as well, other than performance considerations? iPhone call log / history I've installed reCAPTCHA module but spam still bypass my security and leave nasty comments. What should I do? How to block them? Singular or plural following a list Can anyone tell me if I should use inspire or inspires in this phrase?     An extraordinary leader whose vision, values, integrity and boundless curiosity inspires all who follow in his footsteps. How do I turn off some formats in GeoServer's WMS? I have published a couple of layers on my Geoserver.  To be complaint with the T&amp;C of my data provider, I need to block the access of some of those layers as Vector data. Hence I have already blocked the WFS services on these Layers.  I came to know that even on the WMS service, you can get Vector Data, if you use GeoRSS and some of the .   How do I block GeoRSS, SVG &amp; UTFGrid as formats in the WMS Service? I am building a regression model and I need to calculate the below to check for correlations   Correlation between 2 Multi level categorical variables Correlation between a Multi level categorical variable and continuous variable  VIF(variance inflation factor) for a Multi level categorical variables   I believe its wrong to use Pearson correlation coefficient for the above scenarios because Pearson only works for 2 continuous variables.   Please answer the below questions   Which correlation coefficient works best for the above cases ?  VIF calculation only works for continuous data so what is the alternative?  What are the assumptions I need to check before I use the correlation coefficient you suggest?  How to implement them in SAS &amp; R? The phrase "let alone" I notice that "let alone" is used in sentences that have a comma. The structure of the sentence is what comes before the comma is some kind of negative statement. Right after the comma is "let alone," followed by the rest of the sentence.  What does "let alone" mean here? Does it mean the same thing as "or even?" Can someone explain this phrase and sentences that have it? Do "Best by: XX-XX-XX" foods have an expiration date? How long will foods that have "Best by: XX-XX-XX" on the product last past that date?  I have tried looking online, and all I can find is anecdotal evidence, which isn't very assuring for me since there seems to be no specific "x food will expire y weeks after its best by date".  Is there a rule of thumb or some guide out there that can tell me how long a "best by" food will last? Or is it safe to assume that they never expire, since it's not actually labelled on the product? Is there a RegExp.escape function in JavaScript? I just checked my server's /var/log/auth.log and found that I'm getting over 500 failed password/break-in attempt notifications per day! My site is small, and its URL is obscure. Is this normal? Should I be taking any measures? Simple logic problem: Finding largest and smallest number among 3 numbers The latest kernel is causing problems with my sound, which worked fine with an older version. As I have only Ubuntu installed, Grub is not getting displayed while booting. How can I manually choose my kernel version while booting?