On two occasions I have had an error when starting WSJT-X. If you get this error it causes several problems, so getting it fixed right away is essential. If you see this error when you start the program navigate to FILE> Open Log Directory> then open your log file with notepad. In the upper left hand of the log, you will see the header information. Look for the entry with the following: "<eh>", and change it to:"<eoh>" save the file and have a nice day.
There should be a header statement in the log at the top before any log entries are displayed. You may not see this if you have tried to fix the problem by exporting into ADIFMaster or other programs trying to fix the issue. Instead, you may see something like this: WSJT-X ADIF Export<eh>. Simply make your change at this point and continue. Hope this helps, 73, Cly (N4CLY)