903fa16639cacdeb96b1cb4eb8ba706d70c93236
max
  Tue Mar 10 14:46:10 2026 -0700
better err msg, refs #37219

diff --git src/hg/lib/hui.c src/hg/lib/hui.c
index 673443e7f36..195734e801e 100644
--- src/hg/lib/hui.c
+++ src/hg/lib/hui.c
@@ -849,31 +849,31 @@
 // Given a string representation of track visibility, return as equivalent enum.
 {
 int vis = stringArrayIx(s, hTvStrings, ArraySize(hTvStrings));
 if (vis < 0)
     {
     vis = 0;  // don't generate bogus value on invalid input
     }
 return vis;
 }
 
 enum trackVisibility hTvFromString(char *s)
 // Given a string representation of track visibility, return as equivalent enum.
 {
 enum trackVisibility vis = hTvFromStringNoAbort(s);
 if ((int)vis < 0)
-    errAbort("Unknown visibility %s", s);
+    errAbort("Unknown visibility %s. Use one of: hide, dense, squish, pack, full.", s);
 return vis;
 }
 
 char *hStringFromTv(enum trackVisibility vis)
 // Given enum representation convert to string.
 {
 return hTvStrings[vis];
 }
 
 void hTvDropDownClassWithJavascript(char *varName, char *id, enum trackVisibility vis, boolean canPack,
 				char *class, struct slPair *events)
 // Make track visibility drop down for varName with style class
 {
 static char *noPack[] =
     {