OperationalError from SQlite that indicates a permissions problem.

beets/dbcore/db.py

@@ -33,6 +33,15 @@
 import six
 
 
+class DBAccessError(Exception):
+    """The SQLite database became inaccessible.
+
+    This can happen when trying to read or write the database when, for
+    example, the database file is deleted or otherwise disappears. There
+    is probably no way to recover from this error.
+    """
+
+
 class FormattedMapping(collections.Mapping):
     """A `dict`-like formatted view of a model.
 
@@ -680,8 +689,18 @@ def mutate(self, statement, subvals=()):
         """Execute an SQL statement with substitution values and return
         the row ID of the last affected row.
         """
-        cursor = self.db._connection().execute(statement, subvals)
-        return cursor.lastrowid
+        try:
+            cursor = self.db._connection().execute(statement, subvals)
+            return cursor.lastrowid
+        except sqlite3.OperationalError as e:
+            # In two specific cases, SQLite reports an error while accessing
+            # the underlying database file. We surface these exceptions as
+            # DBAccessError so the application can abort.
+            if e.args[0] in ("attempt to write a readonly database",
+                             "unable to open database file"):
+                raise DBAccessError(e.args[0])
+            else:
+                raise
 
     def script(self, statements):
         """Execute a string containing multiple SQL statements."""

beets/ui/__init__.py

@@ -41,6 +41,7 @@
 from beets.util import confit, as_string
 from beets.autotag import mb
 from beets.dbcore import query as db_query
+from beets.dbcore import db
 import six
 
 # On Windows platforms, use colorama to support "ANSI" terminal colors.
@@ -1247,3 +1248,10 @@ def main(args=None):
     except KeyboardInterrupt:
         # Silently ignore ^C except in verbose mode.
         log.debug(u'{}', traceback.format_exc())
+    except db.DBAccessError as exc:
+        log.error(
+            u'database access error: {0}\n'
+            u'the library file might have a permissions problem',
+            exc
+        )
+        sys.exit(1)

docs/changelog.rst

@@ -84,6 +84,8 @@ Fixes:
   AAC codec instead of faac. Thanks to :user:`jansol`. :bug:`2484`
 * Fix import of multidisc releases with subdirectories, which previously
   made each disc be imported separately in different releases. :bug:`2493`
+* When the SQLite database stops being accessible, we now print a friendly
+  error message. Thanks to :user:`Mary011196`. :bug:`1676` :bug:`2508`
 
 
 1.4.3 (January 9, 2017)