1 files changed, 9 insertions, 0 deletions
diff --git a/src/init.cpp b/src/init.cpp
index b48802637b..d1d733af94 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -1210,6 +1210,15 @@ bool AppInitMain(boost::thread_group& threadGroup, CScheduler& scheduler)
     LogPrintf("Using config file %s\n", GetConfigFile(gArgs.GetArg("-conf", BITCOIN_CONF_FILENAME)).string());
     LogPrintf("Using at most %i automatic connections (%i file descriptors available)\n", nMaxConnections, nFD);
 
+    // Warn about relative -datadir path.
+    if (gArgs.IsArgSet("-datadir") && !fs::path(gArgs.GetArg("-datadir", "")).is_absolute()) {
+        LogPrintf("Warning: relative datadir option '%s' specified, which will be interpreted relative to the "
+                  "current working directory '%s'. This is fragile, because if bitcoin is started in the future "
+                  "from a different location, it will be unable to locate the current data files. There could "
+                  "also be data loss if bitcoin is started while in a temporary directory.\n",
+            gArgs.GetArg("-datadir", ""), fs::current_path().string());
+    }
+
     InitSignatureCache();
     InitScriptExecutionCache();