diff --git a/R/operators.R b/R/operators.R
index 8722413f9a..4276666b97 100644
--- a/R/operators.R
+++ b/R/operators.R
@@ -119,26 +119,26 @@ graph.complementer <- function(graph, loops = FALSE) {
 ###################################################################
 
 rename.attr.if.needed <- function(
-  type,
+  type = c("g", "v", "e"),
   graphs,
   newsize = NULL,
   maps = NULL,
   maps2 = NULL,
   ignore = character()
 ) {
+  type <- igraph.match.arg(type)
+
   listfun <- switch(
     type,
     "g" = graph_attr_names,
     "v" = vertex_attr_names,
-    "e" = edge_attr_names,
-    stop("Internal igraph error")
+    "e" = edge_attr_names
   )
   getfun <- switch(
     type,
     "g" = graph_attr,
     "v" = vertex_attr,
-    "e" = edge_attr,
-    stop("Internal igraph error")
+    "e" = edge_attr
   )
   alist <- lapply(graphs, listfun)
   an <- unique(unlist(alist))
@@ -1176,7 +1176,7 @@ path <- function(...) {
     ## Adding named vertices
     res <- add_vertices(e1, length(e2), name = e2)
   } else {
-    cli::cli_abort("Cannot add {.obj_type_friendly type} to igraph graph.")
+    cli::cli_abort("Cannot add {.obj_type_friendly {type}} to igraph graph.")
   }
   res
 }
@@ -1257,7 +1257,7 @@ path <- function(...) {
     res <- delete_vertices(e1, e2)
   } else {
     cli::cli_abort(
-      "Cannot substract {.obj_type_friendly type} from igraph graph."
+      "Cannot substract {.obj_type_friendly {type}} from igraph graph."
     )
   }
   res
@@ -1310,7 +1310,7 @@ rep.igraph <- function(x, n, mark = TRUE, ...) {
     rep.igraph(x, n)
   } else {
     cli::cli_abort(
-      "Cannot multiply igraph graph with {.obj_type_friendly type}."
+      "Cannot multiply igraph graph with {.obj_type_friendly {type}}."
     )
   }
 }
diff --git a/R/plot.common.R b/R/plot.common.R
index 72b07c6d1e..00b7f45616 100644
--- a/R/plot.common.R
+++ b/R/plot.common.R
@@ -542,10 +542,13 @@ i.parse.plot.params <- function(graph, params) {
     }
   }
 
-  func <- function(type, name, range = NULL, dontcall = FALSE) {
-    if (!type %in% names(p)) {
-      stop("Invalid plot option type")
-    }
+  func <- function(
+    type = c("vertex", "edge", "plot"),
+    name,
+    range = NULL,
+    dontcall = FALSE
+  ) {
+    type <- igraph.match.arg(type)
     ret <- function() {
       v <- p[[type]][[name]]
       if (is.function(v) && !dontcall) {
@@ -676,7 +679,7 @@ igraph.check.shapes <- function(x) {
   bad.shapes <- !xx %in% ls(.igraph.shapes)
   if (any(bad.shapes)) {
     bs <- paste(xx[bad.shapes], collapse = ", ")
-    stop("Bad vertex shape(s): ", bs, ".")
+    cli::cli_abort("Bad vertex {cli::qty(length(bad.shapes))} shape{?s}: {bs}.")
   }
   x
 }
diff --git a/R/printr.R b/R/printr.R
index 15ba158d0b..dcc32ac622 100644
--- a/R/printr.R
+++ b/R/printr.R
@@ -195,8 +195,11 @@ head_print_callback <- function(
 #' @export
 
 indent_print <- function(..., .indent = " ", .printer = print) {
-  if (length(.indent) != 1) {
-    stop(".indent must be a scalar")
+  if (length(.indent) != 1 || !is.character(.indent)) {
+    indent <- .indent # cli literal cannot start with a dot
+    cli::cli_abort(
+      "{.arg .indent} must be a character scalar, not {.obj_type_friendly {indent}}."
+    )
   }
 
   opt <- options(width = getOption("width") - nchar(.indent))
diff --git a/R/rewire.R b/R/rewire.R
index 54f5725049..44354e904b 100644
--- a/R/rewire.R
+++ b/R/rewire.R
@@ -40,7 +40,10 @@
 #' print_all(rewire(g, with = keeping_degseq(niter = vcount(g) * 10)))
 rewire <- function(graph, with) {
   if (!is(with, "igraph_rewiring_method")) {
-    stop("'with' is not an igraph rewiring method")
+    cli::cli_abort(
+      "{.arg with} must be an igraph rewiring method, 
+      not {.obj_type_friendly {with}}."
+    )
   }
   do_call(with$fun, list(graph), .args = with$args)
 }
@@ -140,7 +143,10 @@ each_edge <- function(
   multiple <- as.logical(multiple)
   if (mode != 3) {
     if (!multiple) {
-      stop("multiple = FALSE not supported when mode != \"all\"")
+      cli::cli_abort(
+        '{.code multiple = FALSE} is not supported
+         when {.code mode != "all"}'
+      )
     }
     method <- list(
       fun = rewire_each_directed_edge,
diff --git a/R/sgm.R b/R/sgm.R
index 2f8b8a3058..ad7baa465a 100644
--- a/R/sgm.R
+++ b/R/sgm.R
@@ -1,11 +1,22 @@
 solve_LSAP <- function(x, maximum = FALSE) {
-  if (!is.matrix(x) || any(x < 0)) {
-    stop("x must be a matrix with nonnegative entries.")
+  if (!is.matrix(x)) {
+    cli::cli_abort("{.arg x} must be a matrix, not {.obj_type_friendly {x}}.")
+  }
+  if (any(x < 0)) {
+    cli::cli_abort(c(
+      "{.arg x} must not have negative entries.",
+    i = "It has {sum(x<0)} negative entr{?y/ies}."
+    ))
   }
   nr <- nrow(x)
   nc <- ncol(x)
   if (nr > nc) {
-    stop("x must not have more rows than columns.")
+    cli::cli_abort(
+      c(
+      "{.arg x} must not have more rows than columns.",
+    i = "It has {nrow(x)} rows and {ncol(x)} columns."
+    )
+    )
   }
   if (nc > nr) {
     x <- rbind(x, matrix(2 * sum(x), nc - nr, nc))
diff --git a/R/stochastic_matrix.R b/R/stochastic_matrix.R
index f6113d8a86..eb5afe3a6c 100644
--- a/R/stochastic_matrix.R
+++ b/R/stochastic_matrix.R
@@ -83,12 +83,16 @@ stochastic_matrix <- function(
 
   column.wise <- as.logical(column.wise)
   if (length(column.wise) != 1) {
-    stop("`column.wise' must be a logical scalar")
+    cli::cli_abort(
+      "{.arg column.wise} must be a logical scalar, not {.obj_type_friendly {column.wise}}."
+    )
   }
 
   sparse <- as.logical(sparse)
   if (length(sparse) != 1) {
-    stop("`sparse' must be a logical scalar")
+    cli::cli_abort(
+      "{.arg sparse} must be a logical scalar, not {.obj_type_friendly {sparse}}."
+    )
   }
 
   on.exit(.Call(R_igraph_finalizer))
diff --git a/R/versions.R b/R/versions.R
index 27c384b9d9..08520a5d84 100644
--- a/R/versions.R
+++ b/R/versions.R
@@ -92,11 +92,8 @@ upgrade_graph <- function(graph) {
   }
 
   if (g_ver > p_ver) {
-    stop(
-      "Don't know how to downgrade graph from version ",
-      g_ver,
-      " to ",
-      p_ver
+    cli::cli_abort(
+      "Don't know how to downgrade graph from version {g_ver} to {p_ver}."
     )
   }
 
@@ -119,7 +116,9 @@ upgrade_graph <- function(graph) {
 
     graph
   } else {
-    stop("Don't know how to upgrade graph from version ", g_ver, " to ", p_ver)
+    cli::cli_abort(
+      "Don't know how to upgrade graph from version {g_ver} to {p_ver}."
+    )
   }
 }
 
@@ -157,8 +156,9 @@ warn_version <- function(graph) {
     return(TRUE)
   }
 
-  stop(
-    "This graph was created by a new(er) igraph version. Please install the latest version of igraph and try again."
+  cli::cli_abort(
+    "This graph was created by a newer igraph version.
+    Please install the latest version of igraph and try again."
   )
 }
 
diff --git a/tests/testthat/_snaps/versions.md b/tests/testthat/_snaps/versions.md
index d4f2c60662..27d877e05d 100644
--- a/tests/testthat/_snaps/versions.md
+++ b/tests/testthat/_snaps/versions.md
@@ -13,7 +13,7 @@
       upgrade_graph(g)
     Condition
       Error in `upgrade_graph()`:
-      ! Don't know how to upgrade graph from version 0 to 4
+      ! Don't know how to upgrade graph from version 0 to 4.
 
 # we can't upgrade from 0.2 to 1.5.0, on the fly
 
diff --git a/tests/testthat/test-cliques.R b/tests/testthat/test-cliques.R
index 79734f3540..2525e7c253 100644
--- a/tests/testthat/test-cliques.R
+++ b/tests/testthat/test-cliques.R
@@ -159,7 +159,7 @@ test_that("max_cliques() work", {
             numeric()
           }
           if (any(duplicated(PX$PX))) {
-            stop("foo2")
+            cli::cli_abort("foo2")
           }
         }
         pres
diff --git a/tests/testthat/test-glet.R b/tests/testthat/test-glet.R
index af7cd8b615..b6f845f4ff 100644
--- a/tests/testthat/test-glet.R
+++ b/tests/testthat/test-glet.R
@@ -52,10 +52,10 @@ threshold.net <- function(graph, level) {
 
 graphlets.old <- function(graph) {
   if (!is_weighted(graph)) {
-    stop("Graph not weighted")
+    cli::cli_abort("Graph not weighted")
   }
   if (min(E(graph)$weight) <= 0 || any(!is.finite(E(graph)$weight))) {
-    stop("Edge weights must be non-negative and finite")
+    cli::cli_abort("Edge weights must be non-negative and finite")
   }
 
   ## Do all thresholds
@@ -94,10 +94,10 @@ test_that("Graphlets work for a bigger graph", {
 
 graphlets.project.old <- function(graph, cliques, iter, Mu = NULL) {
   if (!is_weighted(graph)) {
-    stop("Graph not weighted")
+    cli::cli_abort("Graph not weighted")
   }
   if (min(E(graph)$weight) <= 0 || any(!is.finite(E(graph)$weight))) {
-    stop("Edge weights must be non-negative and finite")
+    cli::cli_abort("Edge weights must be non-negative and finite")
   }
   if (
     length(iter) != 1 ||
@@ -105,7 +105,7 @@ graphlets.project.old <- function(graph, cliques, iter, Mu = NULL) {
       !is.finite(iter) ||
       iter != as.integer(iter)
   ) {
-    stop("`iter' must be a non-negative finite integer scalar")
+    cli::cli_abort("`iter' must be a non-negative finite integer scalar")
   }
 
   clf <- cliques
diff --git a/tests/testthat/test-structural-properties.R b/tests/testthat/test-structural-properties.R
index 218fd52e3e..f938d495dd 100644
--- a/tests/testthat/test-structural-properties.R
+++ b/tests/testthat/test-structural-properties.R
@@ -160,7 +160,7 @@ test_that("BFS callback does not blow up when an invalid value is returned", {
 
 test_that("BFS callback does not blow up when an error is raised within the callback", {
   callback <- function(graph, data, extra) {
-    stop("test")
+    cli::cli_abort("test")
     FALSE
   }