Add troubleshooting information

README.md

@@ -124,3 +124,19 @@ To upgrade the database after making changes to commit:
 To redo leaderboards:
 
 1. `./script/pear-local_loop recalc_leaderboards`
+
+# Troubleshooting
+
+## ‘Can't write to /usr/local/share/perl/5.30.0 and /usr/local/bin: Installing modules to /home/<username>/perl5’ when running `cpanm` commands
+
+Intall `local::lib` by running the following commands:
+
+```
+  cpanm --local-lib=~/perl5 local::lib && eval $(perl -I ~/perl5/lib/perl5/ -Mlocal::lib)
+```
+
+NB: You must run this in each Terminal window; I don't know why.
+
+## ‘Can't load application from file "<path-to-repo>/script/pear-local_loop": Can't locate Data/UUID.pm in @INC (you may need to install the DATA::UUID module)’ when running server
+
+Ensure you have run the `cpan --installdeps` command.