diff --git a/reference/gmp/functions/gmp-clrbit.xml b/reference/gmp/functions/gmp-clrbit.xml
index fd6f56899b9c..7bf5a41af6ac 100644
--- a/reference/gmp/functions/gmp-clrbit.xml
+++ b/reference/gmp/functions/gmp-clrbit.xml
@@ -50,6 +50,16 @@
   </para>
  </refsect1>
 
+ <refsect1 role="errors">
+  &reftitle.errors;
+  <simpara>
+   Throws a <exceptionname>ValueError</exceptionname> if <parameter>index</parameter> is negative or, as of PHP 8.5.0, too large.
+  </simpara>
+  <simpara>
+   Prior to PHP 8.0.0, an <constant>E_WARNING</constant> was raised instead.
+  </simpara>
+ </refsect1>
+
  <refsect1 role="examples">
   &reftitle.examples;
   <example>
diff --git a/reference/gmp/functions/gmp-fact.xml b/reference/gmp/functions/gmp-fact.xml
index dc58908b1dcb..178f86ba306b 100644
--- a/reference/gmp/functions/gmp-fact.xml
+++ b/reference/gmp/functions/gmp-fact.xml
@@ -41,6 +41,16 @@
   </para>
  </refsect1>
 
+ <refsect1 role="errors">
+  &reftitle.errors;
+  <simpara>
+   Throws a <exceptionname>ValueError</exceptionname> if <parameter>num</parameter> is negative.
+  </simpara>
+  <simpara>
+   Prior to PHP 8.0.0, an <constant>E_WARNING</constant> was raised instead.
+  </simpara>
+ </refsect1>
+
  <refsect1 role="examples">
   &reftitle.examples;
   <para>
diff --git a/reference/gmp/functions/gmp-pow.xml b/reference/gmp/functions/gmp-pow.xml
index 51e7796afa5a..28981a3c19f5 100644
--- a/reference/gmp/functions/gmp-pow.xml
+++ b/reference/gmp/functions/gmp-pow.xml
@@ -51,6 +51,16 @@
   </para>
  </refsect1>
 
+ <refsect1 role="errors">
+  &reftitle.errors;
+  <simpara>
+   Throws a <exceptionname>ValueError</exceptionname> if <parameter>exponent</parameter> is negative.
+  </simpara>
+  <simpara>
+   Prior to PHP 8.0.0, an <constant>E_WARNING</constant> was raised instead.
+  </simpara>
+ </refsect1>
+
  <refsect1 role="examples">
   &reftitle.examples;
   <para>
@@ -63,8 +73,6 @@ $pow1 = gmp_pow("2", 31);
 echo gmp_strval($pow1) . "\n";
 $pow2 = gmp_pow("0", 0);
 echo gmp_strval($pow2) . "\n";
-$pow3 = gmp_pow("2", -1); // Negative exp, generates warning
-echo gmp_strval($pow3) . "\n";
 ?>
 ]]>
     </programlisting>
diff --git a/reference/gmp/functions/gmp-powm.xml b/reference/gmp/functions/gmp-powm.xml
index bb5dffa1cb5d..caa9f1825115 100644
--- a/reference/gmp/functions/gmp-powm.xml
+++ b/reference/gmp/functions/gmp-powm.xml
@@ -14,11 +14,10 @@
    <methodparam><type class="union"><type>GMP</type><type>int</type><type>string</type></type><parameter>exponent</parameter></methodparam>
    <methodparam><type class="union"><type>GMP</type><type>int</type><type>string</type></type><parameter>modulus</parameter></methodparam>
   </methodsynopsis>
-  <para>
+  <simpara>
    Calculate (<parameter>num</parameter> raised into power
-   <parameter>exponent</parameter>) modulo <parameter>modulus</parameter>. If
-   <parameter>exponent</parameter> is negative, result is undefined.
-  </para>
+   <parameter>exponent</parameter>) modulo <parameter>modulus</parameter>.
+  </simpara>
  </refsect1>
 
 
@@ -64,6 +63,20 @@
   </para>
  </refsect1>
 
+ <refsect1 role="errors">
+  &reftitle.errors;
+  <simpara>
+   Throws a <exceptionname>ValueError</exceptionname> if <parameter>exponent</parameter> is negative.
+  </simpara>
+  <simpara>
+   Throws a <exceptionname>DivisionByZeroError</exceptionname> if <parameter>modulus</parameter>
+   is <literal>0</literal>.
+  </simpara>
+  <simpara>
+   Prior to PHP 8.0.0, an <constant>E_WARNING</constant> was raised instead.
+  </simpara>
+ </refsect1>
+
  <refsect1 role="examples">
   &reftitle.examples;
   <para>
diff --git a/reference/gmp/functions/gmp-root.xml b/reference/gmp/functions/gmp-root.xml
index 74b014cee2a7..6b7b50ba14b0 100644
--- a/reference/gmp/functions/gmp-root.xml
+++ b/reference/gmp/functions/gmp-root.xml
@@ -47,6 +47,17 @@
    The integer component of the resultant root, as a GMP number.
   </para>
  </refsect1>
+
+ <refsect1 role="errors">
+  &reftitle.errors;
+  <simpara>
+   Throws a <exceptionname>ValueError</exceptionname> if <parameter>nth</parameter> is less than <literal>1</literal>,
+   or if <parameter>nth</parameter> is even and <parameter>num</parameter> is negative.
+  </simpara>
+  <simpara>
+   Prior to PHP 8.0.0, an <constant>E_WARNING</constant> was raised instead.
+  </simpara>
+ </refsect1>
 </refentry>
 <!-- Keep this comment at the end of the file
 Local variables:
diff --git a/reference/gmp/functions/gmp-rootrem.xml b/reference/gmp/functions/gmp-rootrem.xml
index 7300130f298a..aae4ee1be0ee 100644
--- a/reference/gmp/functions/gmp-rootrem.xml
+++ b/reference/gmp/functions/gmp-rootrem.xml
@@ -49,6 +49,17 @@
    numbers.
   </para>
  </refsect1>
+
+ <refsect1 role="errors">
+  &reftitle.errors;
+  <simpara>
+   Throws a <exceptionname>ValueError</exceptionname> if <parameter>nth</parameter> is less than <literal>1</literal>,
+   or if <parameter>nth</parameter> is even and <parameter>num</parameter> is negative.
+  </simpara>
+  <simpara>
+   Prior to PHP 8.0.0, an <constant>E_WARNING</constant> was raised instead.
+  </simpara>
+ </refsect1>
 </refentry>
 <!-- Keep this comment at the end of the file
 Local variables:
diff --git a/reference/gmp/functions/gmp-scan0.xml b/reference/gmp/functions/gmp-scan0.xml
index 5de0ead1c420..38153f390b8c 100644
--- a/reference/gmp/functions/gmp-scan0.xml
+++ b/reference/gmp/functions/gmp-scan0.xml
@@ -53,6 +53,16 @@
   </para>
  </refsect1>
 
+ <refsect1 role="errors">
+  &reftitle.errors;
+  <simpara>
+   Throws a <exceptionname>ValueError</exceptionname> if <parameter>start</parameter> is negative or, as of PHP 8.5.0, too large.
+  </simpara>
+  <simpara>
+   Prior to PHP 8.0.0, an <constant>E_WARNING</constant> was raised instead.
+  </simpara>
+ </refsect1>
+
  <refsect1 role="examples">
   &reftitle.examples;
   <para>
diff --git a/reference/gmp/functions/gmp-scan1.xml b/reference/gmp/functions/gmp-scan1.xml
index aeff7425e924..130dd88e1bae 100644
--- a/reference/gmp/functions/gmp-scan1.xml
+++ b/reference/gmp/functions/gmp-scan1.xml
@@ -53,6 +53,16 @@
   </para>
  </refsect1>
 
+ <refsect1 role="errors">
+  &reftitle.errors;
+  <simpara>
+   Throws a <exceptionname>ValueError</exceptionname> if <parameter>start</parameter> is negative or, as of PHP 8.5.0, too large.
+  </simpara>
+  <simpara>
+   Prior to PHP 8.0.0, an <constant>E_WARNING</constant> was raised instead.
+  </simpara>
+ </refsect1>
+
  <refsect1 role="examples">
   &reftitle.examples;
   <para>
diff --git a/reference/gmp/functions/gmp-setbit.xml b/reference/gmp/functions/gmp-setbit.xml
index 7b5454714687..dd0c37b90623 100644
--- a/reference/gmp/functions/gmp-setbit.xml
+++ b/reference/gmp/functions/gmp-setbit.xml
@@ -58,6 +58,16 @@
   </para>
  </refsect1>
 
+ <refsect1 role="errors">
+  &reftitle.errors;
+  <simpara>
+   Throws a <exceptionname>ValueError</exceptionname> if <parameter>index</parameter> is negative or too large.
+  </simpara>
+  <simpara>
+   Prior to PHP 8.0.0, an <constant>E_WARNING</constant> was raised instead.
+  </simpara>
+ </refsect1>
+
  <refsect1 role="examples">
   &reftitle.examples;
   <para>
diff --git a/reference/gmp/functions/gmp-sqrt.xml b/reference/gmp/functions/gmp-sqrt.xml
index 31bf4f87875e..a4baff954e70 100644
--- a/reference/gmp/functions/gmp-sqrt.xml
+++ b/reference/gmp/functions/gmp-sqrt.xml
@@ -38,6 +38,16 @@
   </para>
  </refsect1>
 
+ <refsect1 role="errors">
+  &reftitle.errors;
+  <simpara>
+   Throws a <exceptionname>ValueError</exceptionname> if <parameter>num</parameter> is negative.
+  </simpara>
+  <simpara>
+   Prior to PHP 8.0.0, an <constant>E_WARNING</constant> was raised instead.
+  </simpara>
+ </refsect1>
+
  <refsect1 role="examples">
   &reftitle.examples;
   <para>
diff --git a/reference/gmp/functions/gmp-sqrtrem.xml b/reference/gmp/functions/gmp-sqrtrem.xml
index 781c0af02893..5665941006c7 100644
--- a/reference/gmp/functions/gmp-sqrtrem.xml
+++ b/reference/gmp/functions/gmp-sqrtrem.xml
@@ -44,6 +44,16 @@
   </para>
  </refsect1>
 
+ <refsect1 role="errors">
+  &reftitle.errors;
+  <simpara>
+   Throws a <exceptionname>ValueError</exceptionname> if <parameter>num</parameter> is negative.
+  </simpara>
+  <simpara>
+   Prior to PHP 8.0.0, an <constant>E_WARNING</constant> was raised instead.
+  </simpara>
+ </refsect1>
+
  <refsect1 role="examples">
   &reftitle.examples;
   <para>
diff --git a/reference/gmp/functions/gmp-strval.xml b/reference/gmp/functions/gmp-strval.xml
index c6ca69e455ea..aa28b9708151 100644
--- a/reference/gmp/functions/gmp-strval.xml
+++ b/reference/gmp/functions/gmp-strval.xml
@@ -52,6 +52,17 @@
   </para>
  </refsect1>
 
+ <refsect1 role="errors">
+  &reftitle.errors;
+  <simpara>
+   Throws a <exceptionname>ValueError</exceptionname> if <parameter>base</parameter> is not between
+   <literal>2</literal> and <literal>62</literal>, or <literal>-2</literal> and <literal>-36</literal>.
+  </simpara>
+  <simpara>
+   Prior to PHP 8.0.0, an <constant>E_WARNING</constant> was raised instead.
+  </simpara>
+ </refsect1>
+
  <refsect1 role="examples">
   &reftitle.examples;
   <para>
diff --git a/reference/gmp/functions/gmp-testbit.xml b/reference/gmp/functions/gmp-testbit.xml
index ef0f8ec47334..5cf0713cd814 100644
--- a/reference/gmp/functions/gmp-testbit.xml
+++ b/reference/gmp/functions/gmp-testbit.xml
@@ -50,11 +50,12 @@
 
  <refsect1 role="errors">
   &reftitle.errors;
-  <para>
-   An <constant>E_WARNING</constant> level error is issued when 
-   <parameter>index</parameter> is less than zero, and &false;
-   is returned.
-  </para>
+  <simpara>
+   Throws a <exceptionname>ValueError</exceptionname> if <parameter>index</parameter> is negative or, as of PHP 8.5.0, too large.
+  </simpara>
+  <simpara>
+   Prior to PHP 8.0.0, an <constant>E_WARNING</constant> was raised and &false; was returned instead.
+  </simpara>
  </refsect1>
 
  <refsect1 role="examples">