Lightroom encountered a problem and cannot open

[dexhorton]

Lightroom encountered a problem and cannot open.    (Crashed Thread:  0  Dispatch queue: com.apple.main-thread )

It sometimes says it will find the problem and correct it next time it opens.   It does not open.

I am using lightroom CC 2015.   I updated 4 days ago.  My computer is an iMac.  OS X 10.9.5

I have the option of installing Lightroom 5. 

When I tried to solve this problem earlier in December,  my posts were deleted.  My next questions were moderated and not posted.   I am wondering what is happening.  

[dexhorton]

More information:

There are two messages that appear.   They pop up and go away quickly, so it is hard to read.

1)   Lightroom encountered a problem in the preview modules and needs to close.   It will attempt to fix it next time it opens.

and behind that

2)  Lightroom encountered a problem changing modules and must quit.   It will attempt to repair next time it reopens.

Andy help would be appreciated.

[dexhorton · Accepted solution]

For some mysterious reason, the forum put a green star with 'correct answer' by my second comment.   ???   How do I remove that.

After resting for an hour, it seems to be up and working again.    

It appears to be my first time using the software, because it is showing the beginners tutorials at each step.   

[Salome335443640tmx]

how do i fix: lightroom classic encountered a problem and cannot open?