I found this very useful.
SharePoint many times do not display
precise error message and end up with below annoying error with correlation ID.
Below PS command will merge SP log files from ALL servers in farm and gives the
result in *.txt file.
Merge-SPLogFile
-Path C:\log.txt -Correlation 29b5c483-c48b-4ef2-b4b3-f5e29f635d31
