Consider requiring minimum astropy version 4.1
Today we run into a bug that could be traced back to https://github.com/astropy/astropy/pull/9505

The easiest workaround is to drop support for old astropy.

Less easiest to run tests, remote tests with the old dependency combination and the fix all issues that come up. At least the `nasa_exoplanet_archive` module fails on this, but I would not be surprised if there would be more.

(For a failing example: have astropy <4.1 installed, and then run either `pytest astroquery/nasa_exoplanet_carchive --remote-data`, or the following query:

```
>>> from astroquery.nasa_exoplanet_archive import NasaExoplanetArchive
>>> NasaExoplanetArchive.query_object("K2-18 b", cache=False)
``` 
diff --git a/astroquery/vo_conesearch/tests/test_conesearch.py b/astroquery/vo_conesearch/tests/test_conesearch.py
index b2345752..06e977d7 100644
--- a/astroquery/vo_conesearch/tests/test_conesearch.py
+++ b/astroquery/vo_conesearch/tests/test_conesearch.py
@@ -12,6 +12,7 @@ import pytest
 # ASTROPY
 from astropy import units as u
 from astropy.coordinates import ICRS, SkyCoord
+from astropy.io.votable.exceptions import W25
 from astropy.io.votable.tree import Table as VOTable
 from astropy.table import Table
 from astropy.utils.data import get_pkg_data_filename
@@ -50,7 +51,7 @@ class TestConeSearch:
     """
     def setup_class(self):
         # If this link is broken, use the next in database that works
-        self.url = ('http://vizier.u-strasbg.fr/viz-bin/votable/-A?-out.all&'
+        self.url = ('http://vizier.unistra.fr/viz-bin/votable/-A?-out.all&'
                     '-source=I/252/out&')
         self.catname = 'USNO-A2'
 
@@ -81,6 +82,7 @@ class TestConeSearch:
                 service_url=self.url)
         assert result is None
 
+    @pytest.mark.filterwarnings('ignore::astropy.io.votable.exceptions.W25')
     @pytest.mark.parametrize(('center', 'radius'),
                              [((SCS_RA, SCS_DEC), SCS_SR),
                               (SCS_CENTER, SCS_RADIUS)])
@@ -113,7 +115,7 @@ class TestConeSearch:
 
     def test_timeout_classic(self):
         """Test timed out query."""
-        with pytest.warns(NoResultsWarning, match='timed out'):
+        with pytest.warns(W25, match='timed out'):
             with conf.set_temp('timeout', 1e-6):
                 result = conesearch.conesearch(
                     SCS_CENTER, SCS_RADIUS, cache=False,
@@ -142,6 +144,7 @@ class TestConeSearch:
         assert tab_2.url == tab_4.url
         np.testing.assert_array_equal(tab_2.array, tab_4.array)
 
+    @pytest.mark.filterwarnings('ignore::astropy.io.votable.exceptions.W25')
     @pytest.mark.parametrize(('center', 'radius'),
                              [((SCS_RA, SCS_DEC), SCS_SR),
                               (SCS_CENTER, SCS_RADIUS)])
@@ -156,6 +159,7 @@ class TestConeSearch:
 
         assert tab_1.array.size > 0
 
+    @pytest.mark.filterwarnings('ignore::astropy.io.votable.exceptions.W25')
     def test_async(self):
         async_search = conesearch.AsyncConeSearch(
             SCS_CENTER, SCS_RADIUS, return_astropy_table=False)
@@ -172,6 +176,7 @@ class TestConeSearch:
         else:
             assert tab.array.size > 0
 
+    @pytest.mark.filterwarnings('ignore::astropy.io.votable.exceptions.W25')
     def test_async_all(self):
         async_search_all = conesearch.AsyncSearchAll(
             SCS_CENTER, SCS_RADIUS, return_astropy_table=False)
diff --git a/astroquery/vo_conesearch/tests/test_vos_catalog.py b/astroquery/vo_conesearch/tests/test_vos_catalog.py
index d808368e..890cb246 100644
--- a/astroquery/vo_conesearch/tests/test_vos_catalog.py
+++ b/astroquery/vo_conesearch/tests/test_vos_catalog.py
@@ -187,6 +187,7 @@ def test_write_json(tmpdir):
     assert db.list_catalogs_by_url() == db2.list_catalogs_by_url()
 
 
+@pytest.mark.filterwarnings('ignore')
 @pytest.mark.remote_data
 def test_db_from_registry():
     """Test database created from VO registry.
diff --git a/astroquery/vo_conesearch/validator/data/conesearch_urls.txt b/astroquery/vo_conesearch/validator/data/conesearch_urls.txt
index 9792d3ce..241515bc 100644
--- a/astroquery/vo_conesearch/validator/data/conesearch_urls.txt
+++ b/astroquery/vo_conesearch/validator/data/conesearch_urls.txt
@@ -1,12 +1,12 @@
 http://gsss.stsci.edu/webservices/vo/ConeSearch.aspx?CAT=GSC23&amp;
-http://vizier.u-strasbg.fr/viz-bin/conesearch/I/220/out?
-http://vizier.u-strasbg.fr/viz-bin/conesearch/I/243/out?
-http://vizier.u-strasbg.fr/viz-bin/conesearch/I/252/out?
-http://vizier.u-strasbg.fr/viz-bin/conesearch/I/254/out?
-http://vizier.u-strasbg.fr/viz-bin/conesearch/I/255/out?
-http://vizier.u-strasbg.fr/viz-bin/conesearch/I/284/out?
-http://vizier.u-strasbg.fr/viz-bin/conesearch/I/345/gaia2?
-http://vizier.u-strasbg.fr/viz-bin/conesearch/II/246/out?
+http://vizier.unistra.fr/viz-bin/conesearch/I/220/out?
+http://vizier.unistra.fr/viz-bin/conesearch/I/243/out?
+http://vizier.unistra.fr/viz-bin/conesearch/I/252/out?
+http://vizier.unistra.fr/viz-bin/conesearch/I/254/out?
+http://vizier.unistra.fr/viz-bin/conesearch/I/255/out?
+http://vizier.unistra.fr/viz-bin/conesearch/I/284/out?
+http://vizier.unistra.fr/viz-bin/conesearch/I/345/gaia2?
+http://vizier.unistra.fr/viz-bin/conesearch/II/246/out?
 http://wfaudata.roe.ac.uk/sdssdr7-dsa/DirectCone?DSACAT=SDSS_DR7&amp;DSATAB=Galaxy&amp;
 http://wfaudata.roe.ac.uk/sdssdr7-dsa/DirectCone?DSACAT=SDSS_DR7&amp;DSATAB=PhotoObj&amp;
 http://wfaudata.roe.ac.uk/sdssdr7-dsa/DirectCone?DSACAT=SDSS_DR7&amp;DSATAB=PhotoObjAll&amp;
diff --git a/astroquery/vo_conesearch/validator/tests/data/conesearch_good.json b/astroquery/vo_conesearch/validator/tests/data/conesearch_good.json
index 41fd6b8e..30e6fb2f 100644
--- a/astroquery/vo_conesearch/validator/tests/data/conesearch_good.json
+++ b/astroquery/vo_conesearch/validator/tests/data/conesearch_good.json
@@ -30,7 +30,7 @@
             "std_version": "",
             "title": "The USNO-A2.0 Catalogue (Monet+ 1998)",
             "updated": "4/5/2018 10:00:00 AM",
-            "url": "http://vizier.u-strasbg.fr/viz-bin/conesearch/I/252/out?",
+            "url": "http://vizier.unistra.fr/viz-bin/conesearch/I/252/out?",
             "url_use": "base",
             "validate_expected": "good",
             "validate_network_error": null,
@@ -51,4 +51,4 @@
             "wsdl_url": ""
         }
     }
-}
\ No newline at end of file
+}
diff --git a/astroquery/vo_conesearch/validator/tests/data/listcats1.out b/astroquery/vo_conesearch/validator/tests/data/listcats1.out
index a08fa6a6..71b9236f 100644
--- a/astroquery/vo_conesearch/validator/tests/data/listcats1.out
+++ b/astroquery/vo_conesearch/validator/tests/data/listcats1.out
@@ -1,5 +1,5 @@
 The USNO-A2.0 Catalogue (Monet+ 1998) 1
-http://vizier.u-strasbg.fr/viz-bin/conesearch/I/252/out?
+http://vizier.unistra.fr/viz-bin/conesearch/I/252/out?
 W22
 ./results/ac/9c/265b875e219ef4a2f5fe540be28f/vo.xml:15:0: W22: The DEFINITIONS element is deprecated in VOTable 1.1.  Ignoring
 ./results/ac/9c/265b875e219ef4a2f5fe540be28f/vo.xml:15:0: W22: The DEFINITIONS element is deprecated in VOTable 1.1.  Ignoring
diff --git a/astroquery/vo_conesearch/validator/tests/data/listcats2.out b/astroquery/vo_conesearch/validator/tests/data/listcats2.out
index 633da7b1..6fd00e53 100644
--- a/astroquery/vo_conesearch/validator/tests/data/listcats2.out
+++ b/astroquery/vo_conesearch/validator/tests/data/listcats2.out
@@ -1,2 +1,2 @@
 The USNO-A2.0 Catalogue (Monet+ 1998) 1
-http://vizier.u-strasbg.fr/viz-bin/conesearch/I/252/out?
+http://vizier.unistra.fr/viz-bin/conesearch/I/252/out?
diff --git a/astroquery/vo_conesearch/validator/tests/data/printcat.out b/astroquery/vo_conesearch/validator/tests/data/printcat.out
index d8592d38..a12a4b8c 100644
--- a/astroquery/vo_conesearch/validator/tests/data/printcat.out
+++ b/astroquery/vo_conesearch/validator/tests/data/printcat.out
@@ -27,7 +27,7 @@
     "std_version": "",
     "title": "The USNO-A2.0 Catalogue (Monet+ 1998)",
     "updated": "4/5/2018 10:00:00 AM",
-    "url": "http://vizier.u-strasbg.fr/viz-bin/conesearch/I/252/out?",
+    "url": "http://vizier.unistra.fr/viz-bin/conesearch/I/252/out?",
     "url_use": "base",
     "validate_expected": "good",
     "validate_network_error": null,
diff --git a/astroquery/vo_conesearch/validator/tests/data/vao_conesearch_sites_121107_subset.xml b/astroquery/vo_conesearch/validator/tests/data/vao_conesearch_sites_121107_subset.xml
index efe677a1..41e64ee4 100644
--- a/astroquery/vo_conesearch/validator/tests/data/vao_conesearch_sites_121107_subset.xml
+++ b/astroquery/vo_conesearch/validator/tests/data/vao_conesearch_sites_121107_subset.xml
@@ -1,2 +1,2 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<VOTABLE xmlns:vr="http://www.ivoa.net/xml/VOResource/v1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:vs="http://www.ivoa.net/xml/VODataService/v1.1" version="1.2" xmlns="http://www.ivoa.net/xml/VOTable/v1.2"><RESOURCE type="results"><INFO name="QUERY_STATUS" value="OK"/><TABLE><FIELD datatype="char" name="ivoid" arraysize="*"/><FIELD datatype="short" name="cap_index"/><FIELD datatype="char" name="cap_type" arraysize="*"/><FIELD datatype="char" name="cap_description" arraysize="*"/><FIELD datatype="char" name="standard_id" arraysize="*"/><FIELD datatype="short" name="intf_index"/><FIELD datatype="char" name="intf_type" arraysize="*"/><FIELD datatype="char" name="intf_role" arraysize="*"/><FIELD datatype="char" name="std_version" arraysize="*"/><FIELD datatype="char" name="query_type" arraysize="*"/><FIELD datatype="char" name="result_type" arraysize="*"/><FIELD datatype="char" name="wsdl_url" arraysize="*"/><FIELD datatype="char" name="url_use" arraysize="*"/><FIELD datatype="char" name="access_url" arraysize="*"/><FIELD datatype="char" name="res_type" arraysize="*"/><FIELD datatype="char" name="created" arraysize="*"/><FIELD datatype="char" name="creator_seq" arraysize="*"/><FIELD datatype="char" name="content_type" arraysize="*"/><FIELD datatype="char" name="source_format" arraysize="*"/><FIELD datatype="char" name="source_value" arraysize="*"/><FIELD datatype="char" name="res_version" arraysize="*"/><FIELD datatype="float" name="region_of_regard"/><FIELD datatype="char" name="waveband" arraysize="*"/><FIELD datatype="char" name="rights" arraysize="*"/><FIELD datatype="char" name="short_name" arraysize="*"/><FIELD datatype="char" name="res_title" arraysize="*"/><FIELD datatype="char" name="updated" arraysize="*"/><FIELD datatype="char" name="content_level" arraysize="*"/><FIELD datatype="char" name="res_description" arraysize="*"/><FIELD datatype="char" name="reference_url" arraysize="*"/><FIELD datatype="char" name="res_subject" arraysize="*"/><DATA><TABLEDATA><TR><TD>ivo://cds.vizier/i/252</TD><TD>4</TD><TD>conesearch</TD><TD>Cone search capability for table I/252/out (The Full Catalogue)</TD><TD>ivo://ivoa.net/std/conesearch</TD><TD>1</TD><TD>vs:paramhttp</TD><TD>std</TD><TD/><TD/><TD/><TD/><TD>base</TD><TD>http://vizier.u-strasbg.fr/viz-bin/conesearch/I/252/out?</TD><TD>vs:catalogservice</TD><TD>3/28/2008 6:50:02 AM</TD><TD/><TD>catalog</TD><TD>bibcode</TD><TD/><TD>27-Oct-1998</TD><TD/><TD>optical</TD><TD>public</TD><TD>I/252</TD><TD>The USNO-A2.0 Catalogue (Monet+ 1998)</TD><TD>4/5/2018 10:00:00 AM</TD><TD>research</TD><TD>USNO-A2.0 is a catalog of 526,280,881 stars, and is based on a re-reduction of the Precision Measuring Machine (PMM) scans that were the basis for the USNO-A1.0 catalog. The major difference between A2.0 and A1.0 is that A1.0 used the Guide Star Catalog (Lasker et al. 1986, see Cat. &amp;lt;I/220&amp;gt;) as its reference frame whereas A2.0 uses the ICRF as realized by the USNO ACT catalog (Urban et al. 1997, see Cat. II/246&amp;gt;). A2.0 presents right ascension and declination (J2000, epoch of the mean of the blue and red plate) and the blue and red magnitude for each star. Usage of the ACT catalog as well as usage of new astrometric and photometric reduction algorithms should provide improved astrometry (mostly in the reduction of systematic errors) and improved photometry (because the brightest stars on each plate had B and V magnitudes measured by the Tycho experiment on the Hipparcos satellite). The basic format of the catalog and its compilation is the same as for A1.0, and most users should be able to migrate to this newer version with minimal effort.</TD><TD>http://cdsarc.u-strasbg.fr/cgi-bin/Cat?I/252</TD><TD>Positional_Data</TD></TR></TABLEDATA></DATA></TABLE></RESOURCE></VOTABLE>
\ No newline at end of file
+<VOTABLE xmlns:vr="http://www.ivoa.net/xml/VOResource/v1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:vs="http://www.ivoa.net/xml/VODataService/v1.1" version="1.2" xmlns="http://www.ivoa.net/xml/VOTable/v1.2"><RESOURCE type="results"><INFO name="QUERY_STATUS" value="OK"/><TABLE><FIELD datatype="char" name="ivoid" arraysize="*"/><FIELD datatype="short" name="cap_index"/><FIELD datatype="char" name="cap_type" arraysize="*"/><FIELD datatype="char" name="cap_description" arraysize="*"/><FIELD datatype="char" name="standard_id" arraysize="*"/><FIELD datatype="short" name="intf_index"/><FIELD datatype="char" name="intf_type" arraysize="*"/><FIELD datatype="char" name="intf_role" arraysize="*"/><FIELD datatype="char" name="std_version" arraysize="*"/><FIELD datatype="char" name="query_type" arraysize="*"/><FIELD datatype="char" name="result_type" arraysize="*"/><FIELD datatype="char" name="wsdl_url" arraysize="*"/><FIELD datatype="char" name="url_use" arraysize="*"/><FIELD datatype="char" name="access_url" arraysize="*"/><FIELD datatype="char" name="res_type" arraysize="*"/><FIELD datatype="char" name="created" arraysize="*"/><FIELD datatype="char" name="creator_seq" arraysize="*"/><FIELD datatype="char" name="content_type" arraysize="*"/><FIELD datatype="char" name="source_format" arraysize="*"/><FIELD datatype="char" name="source_value" arraysize="*"/><FIELD datatype="char" name="res_version" arraysize="*"/><FIELD datatype="float" name="region_of_regard"/><FIELD datatype="char" name="waveband" arraysize="*"/><FIELD datatype="char" name="rights" arraysize="*"/><FIELD datatype="char" name="short_name" arraysize="*"/><FIELD datatype="char" name="res_title" arraysize="*"/><FIELD datatype="char" name="updated" arraysize="*"/><FIELD datatype="char" name="content_level" arraysize="*"/><FIELD datatype="char" name="res_description" arraysize="*"/><FIELD datatype="char" name="reference_url" arraysize="*"/><FIELD datatype="char" name="res_subject" arraysize="*"/><DATA><TABLEDATA><TR><TD>ivo://cds.vizier/i/252</TD><TD>4</TD><TD>conesearch</TD><TD>Cone search capability for table I/252/out (The Full Catalogue)</TD><TD>ivo://ivoa.net/std/conesearch</TD><TD>1</TD><TD>vs:paramhttp</TD><TD>std</TD><TD/><TD/><TD/><TD/><TD>base</TD><TD>http://vizier.unistra.fr/viz-bin/conesearch/I/252/out?</TD><TD>vs:catalogservice</TD><TD>3/28/2008 6:50:02 AM</TD><TD/><TD>catalog</TD><TD>bibcode</TD><TD/><TD>27-Oct-1998</TD><TD/><TD>optical</TD><TD>public</TD><TD>I/252</TD><TD>The USNO-A2.0 Catalogue (Monet+ 1998)</TD><TD>4/5/2018 10:00:00 AM</TD><TD>research</TD><TD>USNO-A2.0 is a catalog of 526,280,881 stars, and is based on a re-reduction of the Precision Measuring Machine (PMM) scans that were the basis for the USNO-A1.0 catalog. The major difference between A2.0 and A1.0 is that A1.0 used the Guide Star Catalog (Lasker et al. 1986, see Cat. &amp;lt;I/220&amp;gt;) as its reference frame whereas A2.0 uses the ICRF as realized by the USNO ACT catalog (Urban et al. 1997, see Cat. II/246&amp;gt;). A2.0 presents right ascension and declination (J2000, epoch of the mean of the blue and red plate) and the blue and red magnitude for each star. Usage of the ACT catalog as well as usage of new astrometric and photometric reduction algorithms should provide improved astrometry (mostly in the reduction of systematic errors) and improved photometry (because the brightest stars on each plate had B and V magnitudes measured by the Tycho experiment on the Hipparcos satellite). The basic format of the catalog and its compilation is the same as for A1.0, and most users should be able to migrate to this newer version with minimal effort.</TD><TD>http://cdsarc.u-strasbg.fr/cgi-bin/Cat?I/252</TD><TD>Positional_Data</TD></TR></TABLEDATA></DATA></TABLE></RESOURCE></VOTABLE>
diff --git a/astroquery/vo_conesearch/validator/tests/test_validate.py b/astroquery/vo_conesearch/validator/tests/test_validate.py
index 2c12fd1b..5262d19c 100644
--- a/astroquery/vo_conesearch/validator/tests/test_validate.py
+++ b/astroquery/vo_conesearch/validator/tests/test_validate.py
@@ -69,7 +69,7 @@ class TestConeSearchValidation:
         local_outdir = os.path.join(self.out_dir, 'subtmp1')
         local_list = [
             'http://www.google.com/foo&',
-            'http://vizier.u-strasbg.fr/viz-bin/conesearch/I/252/out?']
+            'http://vizier.unistra.fr/viz-bin/conesearch/I/252/out?']
         validate.check_conesearch_sites(destdir=local_outdir,
                                         parallel=parallel,
                                         url_list=local_list)
diff --git a/setup.cfg b/setup.cfg
index 1e6db20b..cd0d72ec 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -43,13 +43,14 @@ filterwarnings =
     ignore::UserWarning
     ignore::astroquery.exceptions.InputWarning
     ignore::astropy.utils.exceptions.AstropyDeprecationWarning
-    ignore::astropy.io.votable.exceptions.W50
-    ignore::astropy.io.votable.exceptions.W06
     ignore::astropy.io.votable.exceptions.W03
+    ignore::astropy.io.votable.exceptions.W06
     ignore::astropy.io.votable.exceptions.W15
-    ignore::astropy.io.votable.exceptions.W49
     ignore::astropy.io.votable.exceptions.W21
+    ignore::astropy.io.votable.exceptions.W22
     ignore::astropy.io.votable.exceptions.W42
+    ignore::astropy.io.votable.exceptions.W49
+    ignore::astropy.io.votable.exceptions.W50
     ignore:leap-second auto-update failed:astropy.utils.exceptions.AstropyWarning
     ignore:numpy.ndarray size changed:RuntimeWarning
     ignore:OverflowError converting::astropy
['astroquery/vo_conesearch/validator/tests/data/vao_conesearch_sites_121107_subset.xml', 'astroquery/vo_conesearch/validator/tests/data/printcat.out', 'astroquery/vo_conesearch/validator/tests/data/conesearch_good.json', 'setup.cfg', 'astroquery/vo_conesearch/tests/test_vos_catalog.py', 'astroquery/vo_conesearch/tests/test_conesearch.py', 'astroquery/vo_conesearch/validator/tests/test_validate.py', 'astroquery/vo_conesearch/validator/tests/data/listcats2.out', 'astroquery/vo_conesearch/validator/data/conesearch_urls.txt', 'astroquery/vo_conesearch/validator/tests/data/listcats1.out']