[tefmocheck] Add check for `could not open file for writing` error.

Bug: 103197
Change-Id: Ie2760dba048ffb1e50a8afa3d696b0fd1ed19472
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/693506
Reviewed-by: Tamir Duberstein <tamird@google.com>
Commit-Queue: Ina Huh <ihuh@google.com>
Reviewed-by: Oliver Newman <olivernewman@google.com>
Fuchsia-Auto-Submit: Ina Huh <ihuh@google.com>
diff --git a/tools/testing/tefmocheck/string_in_log_check.go b/tools/testing/tefmocheck/string_in_log_check.go
index a9b78f7..fa658e3 100644
--- a/tools/testing/tefmocheck/string_in_log_check.go
+++ b/tools/testing/tefmocheck/string_in_log_check.go
@@ -385,6 +385,13 @@
 			String: serialconstants.FailedToFindCursorMsg,
 			Type:   swarmingOutputType,
 		},
+		// For fxbug.dev/103197. Usually indicates an issue with the bot. If the bots
+		// with the failures have been consistently failing with the same error, file
+		// a go/fxif-bug for the suspected bad bots.
+		&stringInLogCheck{
+			String: "server canceled transfer: could not open file for writing",
+			Type:   swarmingOutputType,
+		},
 		// For fxbug.dev/53101.
 		&stringInLogCheck{
 			String: fmt.Sprintf("botanist ERROR: %s", botanistconstants.FailedToStartTargetMsg),