diff --git a/src/init.cpp b/src/init.cpp
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -1847,6 +1847,23 @@
     peerLogic.reset(new PeerLogicValidation(&connman, scheduler));
     RegisterValidationInterface(peerLogic.get());
 
+    // sanitize comments per BIP-0014, format user agent and check total size
+    std::vector<std::string> uacomments;
+    for (const std::string &cmt : gArgs.GetArgs("-uacomment")) {
+        if (cmt != SanitizeString(cmt, SAFE_CHARS_UA_COMMENT))
+            return InitError(strprintf(
+                _("User Agent comment (%s) contains unsafe characters."), cmt));
+        uacomments.push_back(cmt);
+    }
+    const std::string strSubVersion =
+        FormatSubVersion(CLIENT_NAME, CLIENT_VERSION, uacomments);
+    if (strSubVersion.size() > MAX_SUBVERSION_LENGTH) {
+        return InitError(strprintf(
+            _("Total length of network version string (%i) exceeds maximum "
+              "length (%i). Reduce the number or size of uacomments."),
+            strSubVersion.size(), MAX_SUBVERSION_LENGTH));
+    }
+
     if (gArgs.IsArgSet("-onlynet")) {
         std::set<enum Network> nets;
         for (const std::string &snet : gArgs.GetArgs("-onlynet")) {
diff --git a/src/net.cpp b/src/net.cpp
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -3074,28 +3074,15 @@
     std::vector<std::string> uacomments;
     uacomments.push_back("EB" + eb);
 
-    // sanitize comments per BIP-0014, format user agent and check total size
+    // Comments are checked for char compliance at startup, it is safe to add
+    // them to the user agent string
     for (const std::string &cmt : gArgs.GetArgs("-uacomment")) {
-        if (cmt != SanitizeString(cmt, SAFE_CHARS_UA_COMMENT)) {
-            LogPrintf(
-                "User Agent comment (%s) contains unsafe characters. "
-                "We are going to use a sanitize version of the comment.\n",
-                cmt);
-        }
         uacomments.push_back(cmt);
     }
 
+    // Size compliance is checked at startup, it is safe to not check it again
     std::string subversion =
         FormatSubVersion(CLIENT_NAME, CLIENT_VERSION, uacomments);
-    if (subversion.size() > MAX_SUBVERSION_LENGTH) {
-        LogPrintf("Total length of network version string (%i) exceeds maximum "
-                  "length (%i). Reduce the number or size of uacomments. "
-                  "String has been resized to the max length allowed.\n",
-                  subversion.size(), MAX_SUBVERSION_LENGTH);
-        subversion.resize(MAX_SUBVERSION_LENGTH - 2);
-        subversion.append(")/");
-        LogPrintf("Current network string has been set to: %s\n", subversion);
-    }
 
     return subversion;
 }
diff --git a/src/test/net_tests.cpp b/src/test/net_tests.cpp
--- a/src/test/net_tests.cpp
+++ b/src/test/net_tests.cpp
@@ -13,7 +13,6 @@
 #include "streams.h"
 #include "test/test_bitcoin.h"
 
-#include <sstream>
 #include <string>
 
 #include <boost/test/unit_test.hpp>
@@ -59,6 +58,18 @@
     }
 };
 
+class NetTestConfig : public DummyConfig {
+public:
+    bool SetMaxBlockSize(uint64_t maxBlockSize) override {
+        nMaxBlockSize = maxBlockSize;
+        return true;
+    }
+    uint64_t GetMaxBlockSize() const override { return nMaxBlockSize; }
+
+private:
+    uint64_t nMaxBlockSize;
+};
+
 CDataStream AddrmanToStream(CAddrManSerializationMock &_addrman) {
     CDataStream ssPeersIn(SER_DISK, CLIENT_VERSION);
     ssPeersIn << FLATDATA(Params().DiskMagic());
@@ -184,31 +195,19 @@
     BOOST_CHECK_EQUAL(getSubVersionEB(0), "0.0");
 }
 
-BOOST_AUTO_TEST_CASE(test_userAgentLength) {
-    GlobalConfig config;
+BOOST_AUTO_TEST_CASE(test_userAgent) {
+    NetTestConfig config;
 
     config.SetMaxBlockSize(8000000);
-    std::string long_uacomment = "very very very very very very very very very "
-                                 "very very very very very very very very very "
-                                 "very very very very very very very very very "
-                                 "very very very very very very very very very "
-                                 "very very very very very very very very very "
-                                 "very very very very very very very very very "
-                                 "very very very very very very very very very "
-                                 "very very very very very very long comment";
-    gArgs.ForceSetMultiArg("-uacomment", long_uacomment);
-
-    std::ostringstream versionMessage;
-    versionMessage << "/Bitcoin ABC:" << CLIENT_VERSION_MAJOR << "."
-                   << CLIENT_VERSION_MINOR << "." << CLIENT_VERSION_REVISION
-                   << "(EB8.0; very very very very very "
-                      "very very very very very very very very very very very "
-                      "very very very very very very very very very very very "
-                      "very very very very very very very very very very very "
-                      "very very very very very very very ve)/";
-
-    BOOST_CHECK_EQUAL(userAgent(config).size(), MAX_SUBVERSION_LENGTH);
-    BOOST_CHECK_EQUAL(userAgent(config), versionMessage.str());
+    const std::string uacomment = "A very nice comment";
+    gArgs.ForceSetMultiArg("-uacomment", uacomment);
+
+    const std::string versionMessage =
+        "/Bitcoin ABC:" + std::to_string(CLIENT_VERSION_MAJOR) + "." +
+        std::to_string(CLIENT_VERSION_MINOR) + "." +
+        std::to_string(CLIENT_VERSION_REVISION) + "(EB8.0; " + uacomment + ")/";
+
+    BOOST_CHECK_EQUAL(userAgent(config), versionMessage);
 }
 
 BOOST_AUTO_TEST_SUITE_END()