diff --git a/CHANGES.rst b/CHANGES.rst
index 9f01291d..a6d3f91f 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -31,6 +31,7 @@ alma
 - Fixed a regression to handle arrays of string input for the ``query`` methods. [#2094]
 - Throws an error when an unsupported ``kwargs`` (or argument) is passed in to a function. [#2475]
 - New DataLink API handling. [#2493]
+- Fixed bug #2489 in which blank URLs were being sent to the downloader [#2490]
 
 
 astrometry.net
@@ -88,6 +89,12 @@ linelists.cdms
 - Fix issues with the line name parser and the line data parser; the original
   implementation was incomplete and upstream was not fully documented. [#2385, #2411]
 
+mast
+^^^^
+
+- Cull duplicate downloads for the same dataURI in ``Observations.download_products()``
+  and duplicate URIs in ``Observations.get_cloud_uris``. [#2497]
+
 oac
 ^^^
 
@@ -110,6 +117,9 @@ svo_fps
 - Queries with invalid parameter names now raise an ``InvalidQueryError``.
   [#2446]
 
+- The default wavelength range used by ``get_filter_index()`` was far too
+  large. The user must now always specify both upper and lower limits. [#2509]
+
 gaia
 ^^^^
 
diff --git a/astroquery/alma/core.py b/astroquery/alma/core.py
index b41734f6..4368bbbf 100644
--- a/astroquery/alma/core.py
+++ b/astroquery/alma/core.py
@@ -828,7 +828,15 @@ class AlmaClass(QueryWithLogin):
             raise TypeError("Datasets must be given as a list of strings.")
 
         files = self.get_data_info(uids)
-        file_urls = files['access_url']
+        # filter out blank access URLs
+        # it is possible for there to be length-1 lists
+        if len(files) == 1:
+            file_urls = files['access_url']
+            if isinstance(file_urls, str) and file_urls == '':
+                raise ValueError(f"Cannot download uid {uid} because it has no file")
+        else:
+            file_urls = [url for url in files['access_url'] if url]
+
         totalsize = files['content_length'].sum()*u.B
 
         # each_size, totalsize = self.data_size(files)
diff --git a/astroquery/exceptions.py b/astroquery/exceptions.py
index 27651416..8ec2dddf 100644
--- a/astroquery/exceptions.py
+++ b/astroquery/exceptions.py
@@ -7,8 +7,9 @@ from astropy.utils.exceptions import AstropyWarning
 
 __all__ = ['TimeoutError', 'InvalidQueryError', 'RemoteServiceError',
            'TableParseError', 'LoginError', 'ResolverError',
-           'NoResultsWarning', 'LargeQueryWarning', 'InputWarning',
-           'AuthenticationWarning', 'MaxResultsWarning', 'CorruptDataWarning']
+           'NoResultsWarning', 'DuplicateResultsWarning', 'LargeQueryWarning',
+           'InputWarning', 'AuthenticationWarning', 'MaxResultsWarning',
+           'CorruptDataWarning']
 
 
 class TimeoutError(Exception):
@@ -67,6 +68,13 @@ class NoResultsWarning(AstropyWarning):
     pass
 
 
+class DuplicateResultsWarning(AstropyWarning):
+    """
+    Astroquery warning class to be issued when a query returns no result.
+    """
+    pass
+
+
 class LargeQueryWarning(AstropyWarning):
     """
     Astroquery warning class to be issued when a query is larger than
diff --git a/astroquery/mast/observations.py b/astroquery/mast/observations.py
index abe0a0ad..b00f915e 100644
--- a/astroquery/mast/observations.py
+++ b/astroquery/mast/observations.py
@@ -19,7 +19,7 @@ from requests import HTTPError
 import astropy.units as u
 import astropy.coordinates as coord
 
-from astropy.table import Table, Row, vstack, MaskedColumn
+from astropy.table import Table, Row, unique, vstack, MaskedColumn
 from astroquery import log
 
 from astropy.utils import deprecated
@@ -31,7 +31,7 @@ from ..query import QueryWithLogin
 from ..utils import commons, async_to_sync
 from ..utils.class_or_instance import class_or_instance
 from ..exceptions import (TimeoutError, InvalidQueryError, RemoteServiceError,
-                          ResolverError, MaxResultsWarning,
+                          ResolverError, MaxResultsWarning, DuplicateResultsWarning,
                           NoResultsWarning, InputWarning, AuthenticationWarning)
 
 from . import conf, utils
@@ -716,6 +716,9 @@ class ObservationsClass(MastQueryWithLogin):
 
             products = vstack(product_lists)
 
+        # Remove duplicate products
+        products = self._remove_duplicate_products(products)
+
         # apply filters
         products = self.filter_products(products, mrp_only=mrp_only, **filters)
 
@@ -767,6 +770,9 @@ class ObservationsClass(MastQueryWithLogin):
             raise RemoteServiceError('Please enable anonymous cloud access by calling `enable_cloud_dataset` method. '
                                      'See MAST Labs documentation for an example: https://mast-labs.stsci.io/#example-data-access-with-astroquery-observations')
 
+        # Remove duplicate products
+        data_products = self._remove_duplicate_products(data_products)
+
         return self._cloud_connection.get_cloud_uri_list(data_products, include_bucket, full_url)
 
     def get_cloud_uri(self, data_product, *, include_bucket=True, full_url=False):
@@ -802,6 +808,30 @@ class ObservationsClass(MastQueryWithLogin):
         # Query for product URIs
         return self._cloud_connection.get_cloud_uri(data_product, include_bucket, full_url)
 
+    def _remove_duplicate_products(self, data_products):
+        """
+        Removes duplicate data products that have the same dataURI.
+
+        Parameters
+        ----------
+        data_products : `~astropy.table.Table`
+            Table containing products to be checked for duplicates.
+
+        Returns
+        -------
+        unique_products : `~astropy.table.Table`
+            Table containing products with unique dataURIs.
+
+        """
+        number = len(data_products)
+        unique_products = unique(data_products, keys="dataURI")
+        number_unique = len(unique_products)
+        if number_unique < number:
+            warnings.warn(f"{number - number_unique} of {number} products were duplicates."
+                          f"Only downloading {number_unique} unique product(s).", DuplicateResultsWarning)
+
+        return unique_products
+
 
 @async_to_sync
 class MastClass(MastQueryWithLogin):
diff --git a/astroquery/svo_fps/core.py b/astroquery/svo_fps/core.py
index 31bf1d61..6a94b5d8 100644
--- a/astroquery/svo_fps/core.py
+++ b/astroquery/svo_fps/core.py
@@ -9,13 +9,11 @@ from astropy.io.votable import parse_single_table
 from . import conf
 
 from ..query import BaseQuery
-from astroquery.exceptions import InvalidQueryError
+from astroquery.exceptions import InvalidQueryError, TimeoutError
 
 
 __all__ = ['SvoFpsClass', 'SvoFps']
 
-FLOAT_MAX = np.finfo(np.float64).max
-
 # Valid query parameters taken from
 # http://svo2.cab.inta-csic.es/theory/fps/index.php?mode=voservice
 _params_with_range = {"WavelengthRef", "WavelengthMean", "WavelengthEff",
@@ -80,19 +78,17 @@ class SvoFpsClass(BaseQuery):
             # If no table element found in VOTable
             raise IndexError(error_msg)
 
-    def get_filter_index(self, wavelength_eff_min=0*u.angstrom,
-                         wavelength_eff_max=FLOAT_MAX*u.angstrom, **kwargs):
+    def get_filter_index(self, wavelength_eff_min, wavelength_eff_max, **kwargs):
         """Get master list (index) of all filters at SVO
         Optional parameters can be given to get filters data for specified
         Wavelength Effective range from SVO
 
         Parameters
         ----------
-        wavelength_eff_min : `~astropy.units.Quantity` with units of length, optional
-            Minimum value of Wavelength Effective (default is 0 angstrom)
-        wavelength_eff_max : `~astropy.units.Quantity` with units of length, optional
-            Maximum value of Wavelength Effective (default is a very large
-            quantity FLOAT_MAX angstroms i.e. maximum value of np.float64)
+        wavelength_eff_min : `~astropy.units.Quantity` with units of length
+            Minimum value of Wavelength Effective
+        wavelength_eff_max : `~astropy.units.Quantity` with units of length
+            Maximum value of Wavelength Effective
         kwargs : dict
             Passed to `data_from_svo`.  Relevant arguments include ``cache``
 
@@ -104,7 +100,13 @@ class SvoFpsClass(BaseQuery):
         query = {'WavelengthEff_min': wavelength_eff_min.to_value(u.angstrom),
                  'WavelengthEff_max': wavelength_eff_max.to_value(u.angstrom)}
         error_msg = 'No filter found for requested Wavelength Effective range'
-        return self.data_from_svo(query=query, error_msg=error_msg, **kwargs)
+        try:
+            return self.data_from_svo(query=query, error_msg=error_msg, **kwargs)
+        except requests.ReadTimeout:
+            raise TimeoutError(
+                "Query did not finish fast enough. A smaller wavelength range might "
+                "succeed. Try increasing the timeout limit if a large range is needed."
+            )
 
     def get_transmission_data(self, filter_id, **kwargs):
         """Get transmission data for the requested Filter ID from SVO
diff --git a/docs/svo_fps/svo_fps.rst b/docs/svo_fps/svo_fps.rst
index 05fcb6bc..3ec9084e 100644
--- a/docs/svo_fps/svo_fps.rst
+++ b/docs/svo_fps/svo_fps.rst
@@ -1,5 +1,3 @@
-.. doctest-skip-all
-
 .. _astroquery.svo_fps:
 
 **********************************************************
@@ -17,17 +15,19 @@ from the service as astropy tables.
 Get index list of all Filters
 -----------------------------
 
-The filter index (all available filters with their properties) can be listed
-with `~astroquery.svo_fps.SvoFpsClass.get_filter_index`:
+The filter index (the properties of all available filters in a wavelength
+range) can be listed with
+:meth:`~astroquery.svo_fps.SvoFpsClass.get_filter_index`:
 
-.. code-block:: python
+.. doctest-remote-data::
 
+    >>> from astropy import units as u
     >>> from astroquery.svo_fps import SvoFps
-    >>> index = SvoFps.get_filter_index()
+    >>> index = SvoFps.get_filter_index(12_000*u.angstrom, 12_100*u.angstrom)
     >>> index.info
-    <Table masked=True length=5139>
-            name          dtype  unit
-    -------------------- ------- ----
+    <Table length=14>
+            name          dtype        unit
+    -------------------- ------- ---------------
     FilterProfileService  object
                 filterID  object
           WavelengthUnit  object
@@ -41,28 +41,31 @@ with `~astroquery.svo_fps.SvoFpsClass.get_filter_index`:
     CalibrationReference  object
              Description  object
                 Comments  object
-          WavelengthMean float32   AA
-           WavelengthEff float32   AA
-           WavelengthMin float32   AA
-           WavelengthMax float32   AA
-                WidthEff float32   AA
-           WavelengthCen float32   AA
-         WavelengthPivot float32   AA
-          WavelengthPeak float32   AA
-          WavelengthPhot float32   AA
-                    FWHM float32   AA
+           WavelengthRef float64              AA
+          WavelengthMean float64              AA
+           WavelengthEff float64              AA
+           WavelengthMin float64              AA
+           WavelengthMax float64              AA
+                WidthEff float64              AA
+           WavelengthCen float64              AA
+         WavelengthPivot float64              AA
+          WavelengthPeak float64              AA
+          WavelengthPhot float64              AA
+                    FWHM float64              AA
+                    Fsun float64 erg s / (A cm2)
                PhotCalID  object
                   MagSys  object
-               ZeroPoint float32   Jy
+               ZeroPoint float64              Jy
            ZeroPointUnit  object
-                    Mag0 float32
+                    Mag0 float64
            ZeroPointType  object
-               AsinhSoft float32
+               AsinhSoft float64
         TrasmissionCurve  object
 
-There are options to downselect based on the minimum
-and maximum effective wavelength (``wavelength_eff_min``
-and ``wavelength_eff_max``, respectively).
+If the wavelength range contains too many entries then a ``TimeoutError`` will
+occur. A smaller wavelength range might succeed, but if a large range really is
+required then you can use the ``timeout`` argument to allow for a longer
+response time.
 
 Get list of Filters under a specified Facilty and Instrument
 ------------------------------------------------------------
@@ -72,14 +75,13 @@ Filters for an arbitrary combination of Facility & Instrument (the Facility
 must be specified, but the Instrument is optional).  The data table returned
 is of the same form as that from `~astroquery.svo_fps.SvoFpsClass.get_filter_index`:
 
-.. code-block:: python
+.. doctest-remote-data::
 
     >>> filter_list = SvoFps.get_filter_list(facility='Keck', instrument='NIRC2')
     >>> filter_list.info
-
-    <Table masked=True length=11>
-            name          dtype  unit
-    -------------------- ------- ----
+    <Table length=11>
+            name          dtype        unit
+    -------------------- ------- ---------------
     FilterProfileService  object
                 filterID  object
           WavelengthUnit  object
@@ -93,26 +95,27 @@ is of the same form as that from `~astroquery.svo_fps.SvoFpsClass.get_filter_ind
     CalibrationReference  object
              Description  object
                 Comments  object
-          WavelengthMean float32   AA
-           WavelengthEff float32   AA
-           WavelengthMin float32   AA
-           WavelengthMax float32   AA
-                WidthEff float32   AA
-           WavelengthCen float32   AA
-         WavelengthPivot float32   AA
-          WavelengthPeak float32   AA
-          WavelengthPhot float32   AA
-                    FWHM float32   AA
+           WavelengthRef float64              AA
+          WavelengthMean float64              AA
+           WavelengthEff float64              AA
+           WavelengthMin float64              AA
+           WavelengthMax float64              AA
+                WidthEff float64              AA
+           WavelengthCen float64              AA
+         WavelengthPivot float64              AA
+          WavelengthPeak float64              AA
+          WavelengthPhot float64              AA
+                    FWHM float64              AA
+                    Fsun float64 erg s / (A cm2)
                PhotCalID  object
                   MagSys  object
-               ZeroPoint float32   Jy
+               ZeroPoint float64              Jy
            ZeroPointUnit  object
-                    Mag0 float32
+                    Mag0 float64
            ZeroPointType  object
-               AsinhSoft float32
+               AsinhSoft float64
         TrasmissionCurve  object
 
-
 Get transmission data for a specific Filter
 -------------------------------------------
 
@@ -122,40 +125,39 @@ If you know the ``filterID`` of the filter (which you can determine with
 transmission curve data using
 `~astroquery.svo_fps.SvoFpsClass.get_transmission_data`:
 
-.. code-block:: python
+.. doctest-remote-data::
 
     >>> data = SvoFps.get_transmission_data('2MASS/2MASS.H')
     >>> print(data)
     Wavelength Transmission
         AA
     ---------- ------------
-    12890.0          0.0
-    13150.0          0.0
-    13410.0          0.0
-    13680.0          0.0
-    13970.0          0.0
-    14180.0          0.0
-    14400.0       0.0005
-    14620.0       0.0028
-    14780.0       0.0081
-    14860.0       0.0287
-        ...          ...
-    18030.0       0.1077
-    18100.0       0.0707
-    18130.0       0.0051
-    18180.0         0.02
-    18280.0       0.0004
-    18350.0          0.0
-    18500.0        1e-04
-    18710.0          0.0
-    18930.0          0.0
-    19140.0          0.0
+       12890.0          0.0
+       13150.0          0.0
+       13410.0          0.0
+       13680.0          0.0
+       13970.0          0.0
+       14180.0          0.0
+       14400.0       0.0005
+       14620.0 0.0027999999
+       14780.0 0.0081000002
+       14860.0 0.0286999997
+           ...          ...
+       18030.0 0.1076999977
+       18100.0 0.0706999972
+       18130.0 0.0051000002
+       18180.0 0.0199999996
+       18280.0       0.0004
+       18350.0          0.0
+       18500.0       0.0001
+       18710.0          0.0
+       18930.0          0.0
+       19140.0          0.0
     Length = 58 rows
 
-
 These are the data needed to plot the transmission curve for filter:
 
-.. code-block:: python
+.. doctest-skip::
 
     >>> import matplotlib.pyplot as plt
     >>> plt.plot(data['Wavelength'], data['Transmission'])

diff --git a/astroquery/alma/tests/test_alma_remote.py b/astroquery/alma/tests/test_alma_remote.py
index 77068624..077b2d64 100644
--- a/astroquery/alma/tests/test_alma_remote.py
+++ b/astroquery/alma/tests/test_alma_remote.py
@@ -149,7 +149,18 @@ class TestAlma:
         with pytest.raises(AttributeError):
             alma.is_proprietary('uid://NON/EXI/STING')
 
-    @pytest.mark.xfail(reason="Depends on PR 2438 (https://github.com/astropy/astroquery/pull/2438)")
+    def test_retrieve_data(self, temp_path, alma):
+        """
+        Regression test for issue 2490 (the retrieval step will simply fail if
+        given a blank line, so all we're doing is testing that it runs)
+        """
+        alma.cache_location = temp_path
+
+        # small solar TP-only data set (<1 GB)
+        uid = 'uid://A001/X87c/X572'
+
+        alma.retrieve_data_from_uid([uid])
+
     def test_data_info(self, temp_dir, alma):
         alma.cache_location = temp_dir
 
diff --git a/astroquery/mast/tests/test_mast_remote.py b/astroquery/mast/tests/test_mast_remote.py
index 71578c35..7f70ec8d 100644
--- a/astroquery/mast/tests/test_mast_remote.py
+++ b/astroquery/mast/tests/test_mast_remote.py
@@ -14,7 +14,8 @@ import astropy.units as u
 from astroquery import mast
 
 from ..utils import ResolverError
-from ...exceptions import InvalidQueryError, MaxResultsWarning, NoResultsWarning, RemoteServiceError
+from ...exceptions import (InvalidQueryError, MaxResultsWarning, NoResultsWarning,
+                           DuplicateResultsWarning, RemoteServiceError)
 
 
 OBSID = '1647157'
@@ -274,7 +275,7 @@ class TestMast:
                 assert os.path.isfile(row['Local Path'])
 
         # just get the curl script
-        result = mast.Observations.download_products(test_obs[0]["obsid"],
+        result = mast.Observations.download_products(test_obs_id[0]["obsid"],
                                                      download_dir=str(tmpdir),
                                                      curl_flag=True,
                                                      productType=["SCIENCE"],
@@ -283,12 +284,41 @@ class TestMast:
         assert os.path.isfile(result['Local Path'][0])
 
         # check for row input
-        result1 = mast.Observations.get_product_list(test_obs[0]["obsid"])
+        result1 = mast.Observations.get_product_list(test_obs_id[0]["obsid"])
         result2 = mast.Observations.download_products(result1[0])
         assert isinstance(result2, Table)
         assert os.path.isfile(result2['Local Path'][0])
         assert len(result2) == 1
 
+    def test_observations_download_products_no_duplicates(tmpdir):
+
+        # Pull products for a JWST NIRSpec MSA observation with 6 known
+        # duplicates of the MSA configuration file, propID=2736
+        products = mast.Observations.get_product_list("87602009")
+
+        # Filter out everything but the MSA config file
+        mask = np.char.find(products["dataURI"], "_msa.fits") != -1
+        products = products[mask]
+
+        assert len(products) == 6
+
+        # Download the product
+        with pytest.warns(DuplicateResultsWarning):
+            manifest = mast.Observations.download_products(products,
+                                                           download_dir=str(tmpdir))
+
+        # Check that it downloads the MSA config file only once
+        assert len(manifest) == 1
+
+        # enable access to public AWS S3 bucket
+        mast.Observations.enable_cloud_dataset()
+
+        # Check duplicate cloud URIs as well
+        with pytest.warns(DuplicateResultsWarning):
+            uris = mast.Observations.get_cloud_uris(products)
+
+        assert len(uris) == 1
+
     def test_observations_download_file(self, tmpdir):
 
         # enabling cloud connection
diff --git a/astroquery/svo_fps/tests/test_svo_fps.py b/astroquery/svo_fps/tests/test_svo_fps.py
index c2aef041..97a43a48 100644
--- a/astroquery/svo_fps/tests/test_svo_fps.py
+++ b/astroquery/svo_fps/tests/test_svo_fps.py
@@ -1,8 +1,9 @@
 import pytest
 import os
 from astropy import units as u
+from requests import ReadTimeout
 
-from astroquery.exceptions import InvalidQueryError
+from astroquery.exceptions import InvalidQueryError, TimeoutError
 from astroquery.utils.mocks import MockResponse
 from ..core import SvoFps
 
@@ -46,7 +47,9 @@ def get_mockreturn(method, url, params=None, timeout=10, cache=None, **kwargs):
     return MockResponse(content, **kwargs)
 
 
-def test_get_filter_index(patch_get):
+def test_get_filter_index(patch_get, monkeypatch):
+    with pytest.raises(TypeError, match="missing 2 required positional arguments"):
+        SvoFps.get_filter_index()
     lambda_min = TEST_LAMBDA*u.angstrom
     lambda_max = lambda_min + 100*u.angstrom
     table = SvoFps.get_filter_index(lambda_min, lambda_max)
@@ -56,6 +59,17 @@ def test_get_filter_index(patch_get):
     # `get_mockreturn` raises `NotImplementedError`.
     SvoFps.get_filter_index(lambda_min.to(u.m), lambda_max)
 
+    def get_mockreturn_timeout(*args, **kwargs):
+        raise ReadTimeout
+
+    monkeypatch.setattr(SvoFps, '_request', get_mockreturn_timeout)
+    error_msg = (
+        r"^Query did not finish fast enough\. A smaller wavelength range might "
+        r"succeed\. Try increasing the timeout limit if a large range is needed\.$"
+    )
+    with pytest.raises(TimeoutError, match=error_msg):
+        SvoFps.get_filter_index(lambda_min, lambda_max)
+
 
 def test_get_transmission_data(patch_get):
     table = SvoFps.get_transmission_data(TEST_FILTER_ID)

Cannot connect to SVO Filter Profile Service
There seem to be connectivity issues with the SVO Filter Profile Service (FPS). The following code (from the [tutorial](https://astroquery.readthedocs.io/en/latest/svo_fps/svo_fps.html))

```
from astroquery.svo_fps import SvoFps
index = SvoFps.get_filter_index()
```

gives the following error:

```
ReadTimeout: HTTPConnectionPool(host='svo2.cab.inta-csic.es', port=80): Read timed out. (read timeout=60)
```

Since I can access the SVO FPS directly via my web browser, I assume the problem must lie somewhere in the interface between Astroquery and the SVO FPS.

astroquery/svo_fps/tests/test_svo_fps.py::test_get_filter_index astroquery/svo_fps/tests/test_svo_fps.py::test_get_transmission_data astroquery/svo_fps/tests/test_svo_fps.py::test_get_filter_list astroquery/svo_fps/tests/test_svo_fps.py::test_invalid_query