diff --git a/DESCRIPTION b/DESCRIPTION
index 0404421d5c29f071a4a8ac0247cc4b14c5aa3851..49bc02a102267a3b1303a93fdf505f97eae87ffa 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,6 +1,6 @@
 Package: inldata
 Title: Collection of Datasets for the USGS-INL Monitoring Networks
-Version: 1.2.4
+Version: 1.2.5
 Authors@R: c(
     person(given = c("Jason", "C."),
            family = "Fisher", role = c("aut", "cre"),
diff --git a/NEWS.md b/NEWS.md
index dc4e479746830c8988b43a13057a6194f3a99e99..3093d8aa7362829adefa33ce42b5668f10b144b2 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,3 +1,8 @@
+# inldata 1.2.5
+
+- Ensure functions `assert_url` and `download_file` fail gracefully with an informative message
+  if the internet resource is not available (and not give a check warning nor error).
+
 # inldata 1.2.4
 
 - Ensure that unit tests do not fail when the internet connection is unavailable.
diff --git a/R/assert_url.R b/R/assert_url.R
index a7ee0de147b60583813f901846c24dad2760a1e5..8a480d1efdfc2635138093f60c173071f296786f 100644
--- a/R/assert_url.R
+++ b/R/assert_url.R
@@ -9,6 +9,7 @@
 #'   Other arguments passed to the [`httr::HEAD`] and [`httr::GET`] functions.
 #'
 #' @return Returns `url` invisibly.
+#'   A `NULL` value is returned if the assertion fails for any reason.
 #'
 #' @source Code adapted from
 #'   [Stack Overflow](https://stackoverflow.com/questions/52911812/check-if-url-exists-in-r),
@@ -31,6 +32,12 @@ assert_url <- function(url, ...) {
   # check packages
   check_package(pkg = "httr", msg = "URL assertions")
 
+  # check internet connection
+  if (!curl::has_internet()) {
+    message("No internet connection.")
+    return(invisible(NULL))
+  }
+
   f <- safely(httr::HEAD)
   res <- f(url, ...)
 
@@ -39,12 +46,14 @@ assert_url <- function(url, ...) {
     res <- f(url, ...)
     if (is.null(res$result)) {
       sprintf("Assertion on '%s' failed: hard error with no response.", url) |>
-        stop(call. = FALSE)
+        message()
+      return(invisible(NULL))
     }
 
     if (((httr::status_code(res$result) %/% 200) != 1)) {
       sprintf("Assertion on '%s' failed: responded but without an HTTP status code in the 200-299 range.", url) |>
-        stop(call. = FALSE)
+        message()
+      return(invisible(NULL))
     }
   }
 
diff --git a/R/download_file.R b/R/download_file.R
index 5c007df4475808b28f4fe6b9844b96f8cfd29649..cc31f1cfe54da1b6af875fcee0e3f1dd399552a3 100644
--- a/R/download_file.R
+++ b/R/download_file.R
@@ -39,7 +39,11 @@ download_file <- function(url,
   file <- file.path(cachedir, basename(url))
   is <- checkmate::test_file_exists(file, access = "r")
   if (!is) {
-    assert_url(url)
+    url <- assert_url(url)
+    if (is.null(url)) {
+      message("Download failed.")
+      return(invisible(NULL))
+    }
     utils::download.file(
       url = url,
       destfile = file,
diff --git a/R/make_datasets.R b/R/make_datasets.R
index 8e837bfceb7c8da66cb06dfb0515744480f69591..77698214979ea4c5c5a85b0f515b3c2be35b30f5 100644
--- a/R/make_datasets.R
+++ b/R/make_datasets.R
@@ -97,11 +97,6 @@ make_datasets <- function(path = getwd(),
   dt <- Sys.time()
   message("TIMESTAMP: ", format(dt, usetz = TRUE), "\n")
 
-  # check internet connection
-  if (!curl::has_internet()) {
-    stop("No internet connection", call. = FALSE)
-  }
-
   # check arguments
   path <- path.expand(path) |>
     normalizePath(winslash = "/", mustWork = FALSE)
diff --git a/inst/tinytest/test_functions.R b/inst/tinytest/test_functions.R
index b78a2004f5799ed245b8e754da58fa2529794415..f7810997df804f814b7da766d8cdfd860ada312f 100644
--- a/inst/tinytest/test_functions.R
+++ b/inst/tinytest/test_functions.R
@@ -60,18 +60,7 @@ unlink(destdir, recursive = TRUE)
 x <- clean_sf(inl, cols = "geometry", crs = sf::st_crs(3857))
 expect_multi_class(x, classes = c("sf", "data.frame"))
 
-# require internet connection
-if (curl::has_internet()) {
-
-  # test URL assertion
-  expect_silent(assert_url("https://www.usa.gov/"))
-  expect_error(assert_url("https://fail/on/bad/url/"))
-  expect_error(assert_url("https://anyapi.io/api/v1/exchange/rates?base=NAN&apiKey=123"))
-
-  # test downloading file
-  url <- "https://code.usgs.gov/inl/inldata/-/raw/main/CODE_OF_CONDUCT.md"
-  file <- download_file(url, cachedir = tempdir(), quiet = TRUE)
-  expect_file_exists(file, access = "rw")
-  unlink(file)
-
-}
+# test URL assertion
+expect_silent(assert_url("https://www.usa.gov/"))
+expect_null(assert_url("https://fail/on/bad/url/"))
+expect_null(assert_url("https://anyapi.io/api/v1/exchange/rates?base=NAN&apiKey=123"))
diff --git a/inst/tinytest/test_make_datasets.R b/inst/tinytest/test_make_datasets.R
index ffce152ca0332ef383c873462ad70d83d422ca13..bc73c763eedc19ef9a30db91fec1c5eff6741f28 100644
--- a/inst/tinytest/test_make_datasets.R
+++ b/inst/tinytest/test_make_datasets.R
@@ -3,118 +3,113 @@ library("tinytest")
 library("checkmate")
 using("checkmate")
 
-# require internet connection
-if (curl::has_internet()) {
+# test existence of data-raw folder
+destdir <- tempfile("")
+expect_error(
+  current = make_datasets(path = tempdir(), destdir = destdir),
+  pattern = "does not exist"
+)
+unlink(destdir)
 
-  # test existence of data-raw folder
-  destdir <- tempfile("")
-  expect_error(
-    current = make_datasets(path = tempdir(), destdir = destdir),
-    pattern = "does not exist"
-  )
-  unlink(destdir)
+# test making parameters
+pcodes <- "07000"
+n <- length(pcodes)
+x <- inldata:::mds_parameters(pcodes)
+expect_data_frame(x, nrows = n, col.names = "named")
+x <- inldata:::tabulate_parm_data(x, samples)
+expect_data_frame(x, nrows = n, col.names = "named")
 
-  # test making parameters
-  pcodes <- "07000"
-  n <- length(pcodes)
-  x <- inldata:::mds_parameters(pcodes)
-  expect_data_frame(x, nrows = n, col.names = "named")
-  x <- inldata:::tabulate_parm_data(x, samples)
-  expect_data_frame(x, nrows = n, col.names = "named")
+# test making detection limits
+data <- data.frame(
+  "srsname" = c("Tritium", "Tritium"),
+  "pcode" = c("07000", "07000"),
+  "unit_cd" = c("pCi/L", "pCi/L"),
+  "lab_det_lim_va" = c("500", "200"),
+  "min_dt" = c("1949-01-16", "2003-04-01"),
+  "reference" = c("Bartholomay", "Bartholomay")
+)
+x <- inldata:::mds_dl(data, parameters)
+expect_data_frame(x, nrows = nrow(data), col.names = "named")
 
-  # test making detection limits
-  data <- data.frame(
-    "srsname" = c("Tritium", "Tritium"),
-    "pcode" = c("07000", "07000"),
-    "unit_cd" = c("pCi/L", "pCi/L"),
-    "lab_det_lim_va" = c("500", "200"),
-    "min_dt" = c("1949-01-16", "2003-04-01"),
-    "reference" = c("Bartholomay", "Bartholomay")
-  )
-  x <- inldata:::mds_dl(data, parameters)
-  expect_data_frame(x, nrows = nrow(data), col.names = "named")
+# test making benchmarks
+bm <- data.frame(
+  "Chemical Name" = "trans-1,3-Dichloropropene",
+  "CAS Registry Number" = "10061-02-6",
+  "USGS Parameter Code" = "34699",
+  "Chemical Class" = "VOC",
+  "MCL (micrograms/L)" = NA_character_,
+  "Chronic Noncancer HHBP (micrograms/L)" = NA_character_,
+  "Carcinogenic HHBP (micrograms/L)" = NA_character_,
+  "Noncancer HBSL (micrograms/L)" = "200",
+  "Cancer HBSL (micrograms/L)" = "0.3-30",
+  "Benchmark Remarks" = NA_character_,
+  check.names = FALSE
+)
+mcl_extras <- data.frame(
+  "srsname" = "Tritium",
+  "pcode" = "07000",
+  "mcl" = "20000",
+  "unit_cd" = "pCi/L"
+)
+n <- nrow(bm) + nrow(mcl_extras)
+x <- inldata:::mds_benchmarks(bm, mcl_extras, parameters)
+expect_data_frame(x, nrows = n, col.names = "named")
 
-  # test making benchmarks
-  bm <- data.frame(
-    "Chemical Name" = "trans-1,3-Dichloropropene",
-    "CAS Registry Number" = "10061-02-6",
-    "USGS Parameter Code" = "34699",
-    "Chemical Class" = "VOC",
-    "MCL (micrograms/L)" = NA_character_,
-    "Chronic Noncancer HHBP (micrograms/L)" = NA_character_,
-    "Carcinogenic HHBP (micrograms/L)" = NA_character_,
-    "Noncancer HBSL (micrograms/L)" = "200",
-    "Cancer HBSL (micrograms/L)" = "0.3-30",
-    "Benchmark Remarks" = NA_character_,
-    check.names = FALSE
-  )
-  mcl_extras <- data.frame(
-    "srsname" = "Tritium",
-    "pcode" = "07000",
-    "mcl" = "20000",
-    "unit_cd" = "pCi/L"
-  )
-  n <- nrow(bm) + nrow(mcl_extras)
-  x <- inldata:::mds_benchmarks(bm, mcl_extras, parameters)
-  expect_data_frame(x, nrows = n, col.names = "named")
+# test making sites
+data <- data.frame(
+  "agency_cd" = "USGS",
+  "site_no" = "432700112470801",
+  "station_nm" = "02N 31E 35DCC1 USGS 1",
+  "network_cd" = "A",
+  "pos" = "3"
+)
+x <- inldata:::mds_sites(data, crs)
+expect_multi_class(x, classes = c("sf", "data.frame"))
+expect_set_equal(nrow(x), nrow(data))
+y <- inldata:::tabulate_site_data(x, samples, gwl, swm)
+expect_data_frame(y, nrows = nrow(x), col.names = "named")
 
-  # test making sites
-  data <- data.frame(
-    "agency_cd" = "USGS",
-    "site_no" = "432700112470801",
-    "station_nm" = "02N 31E 35DCC1 USGS 1",
-    "network_cd" = "A",
-    "pos" = "3"
-  )
-  x <- inldata:::mds_sites(data, crs)
-  expect_multi_class(x, classes = c("sf", "data.frame"))
-  expect_set_equal(nrow(x), nrow(data))
-  y <- inldata:::tabulate_site_data(x, samples, gwl, swm)
-  expect_data_frame(y, nrows = nrow(x), col.names = "named")
+# test making surface-water measurements
+site_no <- "13131000"
+is <- sites$site_no == site_no
+x <- inldata:::mds_swm(sites = sites[is, ], tz = "America/Denver")
+expect_data_frame(x, min.rows = 1, col.names = "named")
 
-  # test making surface-water measurements
-  site_no <- "13131000"
-  is <- sites$site_no == site_no
-  x <- inldata:::mds_swm(sites = sites[is, ], tz = "America/Denver")
-  expect_data_frame(x, min.rows = 1, col.names = "named")
+# test making groundwater levels
+site_no <- "433500112572501"
+is <- sites$site_no == site_no
+x <- inldata:::mds_gwl(sites = sites[is, ], tz = "America/Denver")
+expect_data_frame(x, min.rows = 1, col.names = "named")
 
-  # test making groundwater levels
-  site_no <- "433500112572501"
-  is <- sites$site_no == site_no
-  x <- inldata:::mds_gwl(sites = sites[is, ], tz = "America/Denver")
-  expect_data_frame(x, min.rows = 1, col.names = "named")
+# test making units
+data <- data.frame(
+  "unit_cd" = "deg C",
+  "unit_ds" = "degrees Celsius"
+)
+x <- inldata:::mds_units(data)
+expect_data_frame(x, nrows = nrow(data), col.names = "named")
 
-  # test making units
-  data <- data.frame(
-    "unit_cd" = "deg C",
-    "unit_ds" = "degrees Celsius"
-  )
-  x <- inldata:::mds_units(data)
-  expect_data_frame(x, nrows = nrow(data), col.names = "named")
+# test making background concentrations
+data <- data.frame(
+  "srsname" = "Sodium",
+  "pcode" = "00930",
+  "unit_cd" = "mg/L",
+  "bkgrd_min" = "8.3",
+  "bkgrd_max" = "14.8",
+  "reference" = "Bartholomay"
+)
+x <- inldata:::mds_background(data, parameters)
+expect_data_frame(x, nrows = nrow(data), col.names = "named")
 
-  # test making background concentrations
-  data <- data.frame(
-    "srsname" = "Sodium",
-    "pcode" = "00930",
-    "unit_cd" = "mg/L",
-    "bkgrd_min" = "8.3",
-    "bkgrd_max" = "14.8",
-    "reference" = "Bartholomay"
-  )
-  x <- inldata:::mds_background(data, parameters)
-  expect_data_frame(x, nrows = nrow(data), col.names = "named")
-
-  # test unit conversion
-  data <- data.frame(
-    "pcode" = c("01065", "00631"),
-    "unit_cd" = c("ug/L", "ug/L")
-  )
-  x <- inldata:::convert_units(data, parameters)
-  expect_data_frame(x,
-    types = c("character", "character", "character", "numeric"),
-    nrows = nrow(data),
-    col.names = "named"
-  )
-  expect_set_equal(colnames(x), c("pcode", "from", "to", "mult"))
-
-}
+# test unit conversion
+data <- data.frame(
+  "pcode" = c("01065", "00631"),
+  "unit_cd" = c("ug/L", "ug/L")
+)
+x <- inldata:::convert_units(data, parameters)
+expect_data_frame(x,
+  types = c("character", "character", "character", "numeric"),
+  nrows = nrow(data),
+  col.names = "named"
+)
+expect_set_equal(colnames(x), c("pcode", "from", "to", "mult"))
diff --git a/man/assert_url.Rd b/man/assert_url.Rd
index bfeadc1aec54a01896f6e30e5330c700278e6578..24d8e1c159b3f82ace9a0291a3af03bdef24b71d 100644
--- a/man/assert_url.Rd
+++ b/man/assert_url.Rd
@@ -19,6 +19,7 @@ URL}
 }
 \value{
 Returns \code{url} invisibly.
+A \code{NULL} value is returned if the assertion fails for any reason.
 }
 \description{
 Assert that a Uniform Resource Locator (URL) is complete and valid.