Usually the problem arises after upgrading firebird 2.5 to 3.
Solution:
- Unistall firebird
- Delete folder C:\Program Files (x86)\Firebird\Firebird_3_0
- Delete fbclient.dll from folder C:\Windows\SysWOW64
- Delete msvcp100.dll from folder C:\Windows\SysWOW64
- Delete msvcr100.dll from folder C:\Windows\SysWOW64
- Install Firebird version 3 again.
Information about firebird files:
https://firebirdsql.org/file/documentation/reference_manuals/user_manuals/html/qsg3-disk-locations.html