When you attempt to open a database with 4D Backup for the purpose of integrating a log file you may get the following error:
"A disk error occurred when opening the file MyFile.
The file is either damaged, locked or opened by another application."

This happens when you attempt to open a structure file (after clicking Restore Log) that stores an invalid pathname to a data file. There are three options to work around this problem:

When you backup the data file, backup the structure file as well. This guaranties the reference to the data file will be valid.
Open the structure file with 4D/4D Server and select the data file you want to integrate the log into. This workaround is invalid if, for example, the data is altered by the On startup method.
You can also attempt to modify the name and location of the data file so that it matches the name/location of the previous data file opened with that structure.