I had the same problems with Plan-G 3.14 in failing to build the database for P3Dv4. During the last two days I tried finding the issues. So now I have a bunch of airports which cause the failing:
Already known: Rome Ciampino and Porto Santo (Madeira); then in addition I deactivated KSEA (T2G), TFFR, CYPR, EDAH (C7) and all Patches from Simmershome for the German Airports to be used in P3Dv4 (I don't known why). With all theses Sceneries deactivated I was lucky in building the data base. Probabely this may help the one or the other. For your information: the log-file for Plan-G gives you the name of the airport which causes the failure (but only one per run - so you have try several time) in the log file; example: 21:30:54.8 Schreibe 25814 Flugplätze
21:30:55.1 Error writing airport: EDDW Bremen)
Hope the helps a little bit.
Best regards
Bernhard
Already known: Rome Ciampino and Porto Santo (Madeira); then in addition I deactivated KSEA (T2G), TFFR, CYPR, EDAH (C7) and all Patches from Simmershome for the German Airports to be used in P3Dv4 (I don't known why). With all theses Sceneries deactivated I was lucky in building the data base. Probabely this may help the one or the other. For your information: the log-file for Plan-G gives you the name of the airport which causes the failure (but only one per run - so you have try several time) in the log file; example: 21:30:54.8 Schreibe 25814 Flugplätze
21:30:55.1 Error writing airport: EDDW Bremen)
Hope the helps a little bit.
Best regards
Bernhard