After a library problem Arduino crashes when launched

Arduino 1.8.8 launched OK today but then had a library problem where something was named with a space in it - apparently. When opening the library editor the window was empty and shortly afterward the program simply dropped out. It had worked OK the day before and nothing else was installed.
Restarted the application and the splash screen appears - then the program simply drops out. I cannot find a way to get the application to start up again other than restarting the Mac itself and then all works OK again. Downright annoying as I usually have several other apps open and have to close everything down to continue programming.
Had this happen about 3 or 4 times now and installing an earlier version gives the same problem unless I restart the Mac.
Tried renaming Arduino15 folder but no change!
Using iMac 27", Mojave 10.14.2 OS, 3.2GHz Core i5, 24GB memory installed

I just installed 1.8.5 on Ubuntu. you need the patience of a monk. I have the patience of a monkey. it is worse on the Raspberry Pi

the thing is, I prefer to keep multiple copies of libraries, because I have found them all AWOL more than once. The Arduino IDE installer for Ubuntu that actually works puts the library at

home/username/snap/arduino-mhall119/current/Arduino/libraries

AND!

home/username/Arduino/libraries

and the IDE cries like a girl if you have more than one copy of the same library, and it finds them in and gets them from yet another place.

you have to find which library directory it is using, and put a copy there. it tells you where it found the library it is using in the "there is always something to complain about" box at the bottom of the page.

That is the Arduino IDE installation folder. If you're saving anything to that folder then you shouldn't be surprised to see it go "AWOL". Everything in that folder is lost when you update to a new version of the Arduino IDE. That is why you should only install things to the sketchbook folder (configured at File > Preferences > Sketchbook Location). The sketchbook folder persists through IDE updates.

FYI, that "mhall119" snap package is an unofficial, outdated, and randomly modified version of the Arduino IDE. My recommendation is to always use the official Arduino IDE, which is downloaded here:

If you install multiple copies of a library then yes the Arduino IDE is going to tell you that multiple libraries were found that match your #include directive. This is extremely useful information. If it didn't tell you that then I'm sure you'd eventually be here complaining "I thought the IDE was using this copy of the library but after days of work I found out it was using that other copy. Why doesn't it tell you which one it's using?".

Installing multiple copies of a library in multiple locations because you're afraid one will go "AWOL" is just silly, and will eventually lead to confusion and wasted time. If you're concerned about files going "AWOL", then do what everyone else does and back up your files!

FYI, that "mhall119" snap package is an unofficial, outdated, and randomly modified version of the Arduino IDE. My recommendation is to always use the official Arduino IDE, which is downloaded here:

there are a dozen web pages that tell you how to install a more modern IDE on Ubuntu. every one of them have a post in which someone quotes the same error message I get. nobody replies to those posts. whatever problems that mhall installation may have are negated by the fact that it appears to be the only reliable way to get a new IDE on Ubuntu

What is this mysterious error message you're getting? Please post the full error.

[quote author=Geek Emeritus link=msg=4044825 date=1549230710]it appears to be the only reliable way to get a new IDE on Ubuntu
[/quote]
If by "new", you mean outdated by over a year. The current version of the Arduino IDE is 1.8.8.