Author Alan, 5B4AHJ

There are three separate DXCC entities involving German callsigns, as follows:

ADIF Name ADIF DXCC No DXCC status Abbreviation
Germany 81 Deleted  
German Dem Rep 229 Deleted GDR
Fed Rep Germany 230 Current FRG

The above information is taken from the ADIF specification

How is all this related to dates and prefixes?

DXCC Valid QSO Dates Prefixes Note  
Germany Before 1973-09-17 D2 D4 D5 DA-DL DM DT  
GDR 1973-09-17 to 1990-10-02 DM DT
Y2-Y9 (from circa 1979)
See table below
FRG 1973-09-17 to now DA-DD DF-DH DJ-DL DN-DQ (current) and DM from 1990-10-03, DT from 1973-09-17 to 1979-12-31, Y2-Y9 from 1990-10-03 to 1994-12-31 (verification of this latter date is required).  

The above information is from the RSGB Prefix Guide.

Why do I get error messages about German callsigns in my upload report?

You get these messages in cases where your logging software does not map German callsigns according to the above information.
In these cases, you should encourage the person who maintains your logging software's country database to update the mappings in accordance with the above.

GDR stations before 1970-09-17
Although GDR was formed in 1949, QSOs with GDR stations did not count for the DXCC entity of GDR until 1973-09-17. QSLs for QSOs before that date may state "German Democratic Republic", but, for DXCC purposes, count for the deleted entity of Germany. DM2ARE was one such station.

GDR stations from 1980-01-01

The following information is taken from DX News Sheet #877, dated 1979-08-29, published by Geoff Watts.

DM stations were issued with new callsigns. New callsigns for GDR were allocated in accordance with the following table.
These new prefixes came into effect on 1980-01-01 (from DXNS#895).

The Club Log QSO database contains Y## callsigns that pre-date 1980-01-01 (with dates as early as 1973). Information required on whether these callsigns were personal callsigns, special event callsigns or other.

Callsign Usage
Y21A-Y29Z Repeaters
Y21AA-Y29ZZ Personal callsigns
Y31A-Y31Z Contest callsigns
Y31AA-Y39ZZ Club stations
Y41A-Y49Z Beacons
Y61A-Y61Z News bulletin stations
Y91AA-Y99ZZ Club stations

The last letter of the suffix denoted the district that the callsign was QRV from.

Last letter of suffix District
A, U Rostock
B Schwerin
C Neubrandenberg
D, P Potsdam
E Frankfurt
F,X Cottbus
G,W Magdeburg
H,V Halle
I,Q Erfurt
J,Y Gera
K Suhl
L,R Dresden
M,S Leipzig
N,T Karl-Marx-Stadt
O Berlin

DXNS #1279, dated 1987-08-05, reports that "DL stations have been appending /60 to celebrate 60 years of han radio in West Germany. The suffix is 'six-zero', not 'six-oh' and has no connection with Somalia!!"

Ex GDR stations 1992 and later

DXNS #1522, dated 1992-06-24, reports : "The old East German callsigns with a Y prefix will be converted to callsigns in the DL1..DL9 series by the end of 1992".