diff --git a/base/loading.jl b/base/loading.jl
index 5034824e6a187..ca6751c2b9620 100644
--- a/base/loading.jl
+++ b/base/loading.jl
@@ -210,7 +210,6 @@ function _require_search_from_serialized(node::Int, mod::Symbol, sourcepath::Str
         paths = @fetchfrom node find_all_in_cache_path(mod)
     end
 
-    local restored = nothing, failedpath = ""
     for path_to_try in paths::Vector{String}
         if stale_cachefile(sourcepath, path_to_try)
             continue
@@ -220,7 +219,7 @@ function _require_search_from_serialized(node::Int, mod::Symbol, sourcepath::Str
             if isa(restored, ErrorException) && endswith(restored.msg, " uuid did not match cache file.")
                 # can't use this cache due to a module uuid mismatch,
                 # defer reporting error until after trying all of the possible matches
-                failedpath = path_to_try
+                DEBUG_LOADING[] && info(restored, prefix="INFO: JL_DEBUG_LOADING: Failed to load $path_to_try because ")
                 continue
             end
             warn("Deserialization checks failed while attempting to load cache from $path_to_try.")
@@ -229,13 +228,14 @@ function _require_search_from_serialized(node::Int, mod::Symbol, sourcepath::Str
             return restored
         end
     end
-    if isa(restored, Exception)
-        warn("Deserialization checks failed while attempting to load cache from $failedpath.")
-        warn(restored, prefix="WARNING: ")
-    end
     return !isempty(paths)
 end
 
+# this value is set by `require` based on whether JULIA_DEBUG_LOADING
+# is presently defined as an environment variable
+# and makes the logic in this file noisier about what it is doing and why
+const DEBUG_LOADING = Ref(false)
+
 # to synchronize multiple tasks trying to import/using something
 const package_locks = Dict{Symbol,Condition}()
 
@@ -341,7 +341,7 @@ during package development as code is modified.
 function reload(name::AbstractString)
     if isfile(name) || contains(name,Filesystem.path_separator)
         # for reload("path/file.jl") just ask for include instead
-        error("use `include` instead of `reload` to load source files")
+        error("Use `include` instead of `reload` to load source files.")
     else
         # reload("Package") is ok
         require(Symbol(require_modname(name)))
@@ -375,6 +375,7 @@ function require(mod::Symbol)
     # and is not applied recursively to imported modules:
     old_track_dependencies = _track_dependencies[]
     _track_dependencies[] = false
+    DEBUG_LOADING[] = haskey(ENV, "JULIA_DEBUG_LOADING")
 
     global toplevel_load
     loading = get(package_locks, mod, false)
@@ -392,7 +393,7 @@ function require(mod::Symbol)
         name = string(mod)
         path = find_in_node_path(name, nothing, 1)
         if path === nothing
-            throw(ArgumentError("module $name not found in current path.\nRun `Pkg.add(\"$name\")` to install the $name package."))
+            throw(ArgumentError("Module $name not found in current path.\nRun `Pkg.add(\"$name\")` to install the $name package."))
         end
 
         # attempt to load the module file via the precompile cache locations
@@ -410,6 +411,10 @@ function require(mod::Symbol)
             if mod === concrete_mod
                 warn("""Module $mod with uuid $concrete_uuid is missing from the cache.
                      This may mean module $mod does not support precompilation but is imported by a module that does.""")
+                if JLOptions().incremental != 0
+                    # during incremental precompilation, this should be fail-fast
+                    throw(PrecompilableError(false))
+                end
             end
         end
 
@@ -419,8 +424,9 @@ function require(mod::Symbol)
             cachefile = compilecache(mod)
             m = _require_from_serialized(1, mod, cachefile, last)
             if isa(m, Exception)
-                warn("Compilecache failed to create a usable precompiled cache file for module $name. Got:")
+                warn("`compilecache` failed to create a usable precompiled cache file for module $name. Got:")
                 warn(m, prefix="WARNING: ")
+                # fall-through
             else
                 return # success
             end
@@ -448,7 +454,7 @@ function require(mod::Symbol)
             m = _require_from_serialized(1, mod, cachefile, last)
             if isa(m, Exception)
                 warn(m, prefix="WARNING: ")
-                error("module $mod declares __precompile__(true) but require failed to create a usable precompiled cache file.")
+                error("Module $mod declares __precompile__(true) but require failed to create a usable precompiled cache file.")
             end
         end
     finally
@@ -629,7 +635,7 @@ function compilecache(name::String)
         end
     end
     # run the expression and cache the result
-    if isinteractive()
+    if isinteractive() || DEBUG_LOADING[]
         if isfile(cachefile)
             info("Recompiling stale cache file $cachefile for module $name.")
         else
@@ -637,7 +643,7 @@ function compilecache(name::String)
         end
     end
     if !success(create_expr_cache(path, cachefile, concrete_deps))
-        error("Failed to precompile $name to $cachefile")
+        error("Failed to precompile $name to $cachefile.")
     end
     return cachefile
 end
@@ -662,9 +668,7 @@ function parse_cache_header(f::IO)
         n = ntoh(read(f, Int32))
         n == 0 && break
         totbytes -= 4 + n + 8
-        if n < 0 # probably means this wasn't a valid file to be read by Base.parse_cache_header
-            error("EOF while reading cache header")
-        end
+        @assert n >= 0 "EOF while reading cache header" # probably means this wasn't a valid file to be read by Base.parse_cache_header
         push!(files, (String(read(f, n)), ntoh(read(f, Float64))))
     end
     @assert totbytes == 4 "header of cache file appears to be corrupt"
@@ -674,7 +678,7 @@ end
 function parse_cache_header(cachefile::String)
     io = open(cachefile, "r")
     try
-        !isvalid_cache_header(io) && throw(ArgumentError("invalid cache file $cachefile"))
+        !isvalid_cache_header(io) && throw(ArgumentError("Invalid header in cache file $cachefile."))
         return parse_cache_header(io)
     finally
         close(io)
@@ -697,7 +701,7 @@ end
 function cache_dependencies(cachefile::String)
     io = open(cachefile, "r")
     try
-        !isvalid_cache_header(io) && throw(ArgumentError("invalid cache file $cachefile"))
+        !isvalid_cache_header(io) && throw(ArgumentError("Invalid header in cache file $cachefile."))
         return cache_dependencies(io)
     finally
         close(io)
@@ -708,28 +712,35 @@ function stale_cachefile(modpath::String, cachefile::String)
     io = open(cachefile, "r")
     try
         if !isvalid_cache_header(io)
+            DEBUG_LOADING[] && info("JL_DEBUG_LOADING: Rejecting cache file $cachefile due to it containing an invalid cache header.")
             return true # invalid cache file
         end
         modules, files = parse_cache_header(io)
 
         # check if this file is going to provide one of our concrete dependencies
-        provides_concrete = false
-        for (mod, uuid) in _concrete_dependencies
-            if get(modules, mod, UInt64(0)) === uuid
-                provides_concrete = true
-            else
-                return false # cachefile doesn't provide the required version of the dependency
+        # or if it provides a version that conflicts with our concrete dependencies
+        # or neither
+        for (mod, uuid_req) in _concrete_dependencies
+            uuid = get(modules, mod, UInt64(0))
+            if uuid !== UInt64(0)
+                if uuid === uuid_req
+                    return false # this is the file we want
+                end
+                DEBUG_LOADING[] && info("JL_DEBUG_LOADING: Rejecting cache file $cachefile because it provides the wrong uuid (got $uuid) for $mod (want $uuid_req).")
+                return true # cachefile doesn't provide the required version of the dependency
             end
         end
-        provides_concrete && return false # this is the file we want
 
         # now check if this file is fresh relative to its source files
         if files[1][1] != modpath
+            DEBUG_LOADING[] && info("JL_DEBUG_LOADING: Rejecting cache file $cachefile because it is for file $(files[1][1])) not file $modpath.")
             return true # cache file was compiled from a different path
         end
-        for (f, ftime) in files
+        for (f, ftime_req) in files
             # Issue #13606: compensate for Docker images rounding mtimes
-            if mtime(f) ∉ (ftime, floor(ftime))
+            ftime = mtime(f)
+            if ftime != ftime_req && ftime != floor(ftime_req)
+                DEBUG_LOADING[] && info("JL_DEBUG_LOADING: Rejecting stale cache file $cachefile (mtime $ftime_req) because file $f (mtime $ftime) is updated.")
                 return true
             end
         end
diff --git a/base/util.jl b/base/util.jl
index ff43543ec6f7e..ad0d06e4d77b5 100644
--- a/base/util.jl
+++ b/base/util.jl
@@ -383,6 +383,12 @@ warn(io::IO, err::Exception; prefix="ERROR: ", kw...) =
 warn(err::Exception; prefix="ERROR: ", kw...) =
     warn(STDERR, err, prefix=prefix; kw...)
 
+info(io::IO, err::Exception; prefix="ERROR: ", kw...) =
+    info(io, sprint(buf->showerror(buf, err)), prefix=prefix; kw...)
+
+info(err::Exception; prefix="ERROR: ", kw...) =
+    info(STDERR, err, prefix=prefix; kw...)
+
 function julia_cmd(julia=joinpath(JULIA_HOME, julia_exename()))
     opts = JLOptions()
     cpu_target = unsafe_string(opts.cpu_target)
diff --git a/test/compile.jl b/test/compile.jl
index f49de8f02d590..d879ef42a0c07 100644
--- a/test/compile.jl
+++ b/test/compile.jl
@@ -16,6 +16,11 @@ function redirected_stderr(expected)
     return t
 end
 
+# this environment variable would affect some error messages being tested below
+# so we disable it for the tests below
+withenv("JULIA_DEBUG_LOADING"=>"") do
+delete!(ENV, "JULIA_DEBUG_LOADING")
+
 olderr = STDERR
 dir = mktempdir()
 dir2 = mktempdir()
@@ -225,11 +230,7 @@ try
     @test !Base.stale_cachefile(FooBar1_file, joinpath(dir2, "FooBar1.ji"))
     @test !Base.stale_cachefile(FooBar_file, joinpath(dir2, "FooBar.ji"))
 
-    t = redirected_stderr("""
-                          WARNING: Deserialization checks failed while attempting to load cache from $(joinpath(dir2, "FooBar1.ji")).
-                          WARNING: Module FooBar uuid did not match cache file.
-                          WARNING: replacing module FooBar1.
-                          """)
+    t = redirected_stderr("WARNING: replacing module FooBar1.")
     try
         reload("FooBar1")
     finally
@@ -331,3 +332,5 @@ let module_name = string("a",randstring())
     deleteat!(LOAD_PATH,1)
     rm(file_name)
 end
+
+end # !withenv