diff --git a/src/ass_exporter.cpp b/src/ass_exporter.cpp
index 1935284cb..777f967eb 100644
--- a/src/ass_exporter.cpp
+++ b/src/ass_exporter.cpp
@@ -67,8 +67,7 @@ void AssExporter::DrawSettings(wxWindow *parent, wxSizer *target_sizer) {
 
 void AssExporter::AddFilter(std::string const& name) {
 	auto filter = AssExportFilterChain::GetFilter(name);
-
-	if (!filter) throw "Filter not found: " + name;
+	if (!filter) throw agi::InternalError("Filter not found: " + name);
 
 	filters.push_back(filter);
 }
@@ -90,7 +89,7 @@ void AssExporter::Export(agi::fs::path const& filename, std::string const& chars
 
 	const SubtitleFormat *writer = SubtitleFormat::GetWriter(filename);
 	if (!writer)
-		throw "Unknown file type.";
+		throw agi::InvalidInputException("Unknown file type.");
 
 	writer->WriteFile(&subs, filename, c->project->Timecodes(), charset);
 }
@@ -104,5 +103,5 @@ std::string const& AssExporter::GetDescription(std::string const& name) const {
 	auto filter = AssExportFilterChain::GetFilter(name);
 	if (filter)
 		return filter->GetDescription();
-	throw "Filter not found: " + name;
+	throw agi::InternalError("Filter not found: " + name);
 }
diff --git a/src/async_video_provider.cpp b/src/async_video_provider.cpp
index ba9cbe287..d1b6fbce9 100644
--- a/src/async_video_provider.cpp
+++ b/src/async_video_provider.cpp
@@ -58,7 +58,7 @@ std::shared_ptr<VideoFrame> AsyncVideoProvider::ProcFrame(int frame_number, doub
 			}
 		}
 	}
-	catch (std::string const& err) { throw SubtitlesProviderErrorEvent(err); }
+	catch (agi::Exception const& err) { throw SubtitlesProviderErrorEvent(err.GetMessage()); }
 
 	try {
 		subs_provider->DrawSubtitles(*frame, time / 1000.);
@@ -72,8 +72,8 @@ static std::unique_ptr<SubtitlesProvider> get_subs_provider(wxEvtHandler *evt_ha
 	try {
 		return SubtitlesProviderFactory::GetProvider(br);
 	}
-	catch (std::string const& err) {
-		evt_handler->AddPendingEvent(SubtitlesProviderErrorEvent(err));
+	catch (agi::Exception const& err) {
+		evt_handler->AddPendingEvent(SubtitlesProviderErrorEvent(err.GetMessage()));
 		return nullptr;
 	}
 }
diff --git a/src/audio_provider_ffmpegsource.cpp b/src/audio_provider_ffmpegsource.cpp
index 9e9e9183f..3a89f6506 100644
--- a/src/audio_provider_ffmpegsource.cpp
+++ b/src/audio_provider_ffmpegsource.cpp
@@ -78,11 +78,8 @@ FFmpegSourceAudioProvider::FFmpegSourceAudioProvider(agi::fs::path const& filena
 
 	LoadAudio(filename);
 }
-catch (std::string const& err) {
-	throw agi::AudioProviderOpenError(err);
-}
-catch (const char *err) {
-	throw agi::AudioProviderOpenError(err);
+catch (agi::EnvironmentError const& err) {
+	throw agi::AudioProviderOpenError(err.GetMessage());
 }
 
 void FFmpegSourceAudioProvider::LoadAudio(agi::fs::path const& filename) {
diff --git a/src/command/subtitle.cpp b/src/command/subtitle.cpp
index 24175191c..02bc640cf 100644
--- a/src/command/subtitle.cpp
+++ b/src/command/subtitle.cpp
@@ -322,9 +322,6 @@ static void save_subtitles(agi::Context *c, agi::fs::path filename) {
 	catch (const agi::Exception& err) {
 		wxMessageBox(to_wx(err.GetMessage()), "Error", wxOK | wxICON_ERROR | wxCENTER, c->parent);
 	}
-	catch (const char *err) {
-		wxMessageBox(err, "Error", wxOK | wxICON_ERROR | wxCENTER, c->parent);
-	}
 	catch (...) {
 		wxMessageBox("Unknown error", "Error", wxOK | wxICON_ERROR | wxCENTER, c->parent);
 	}
diff --git a/src/dialog_export.cpp b/src/dialog_export.cpp
index f038bf1b7..79f649170 100644
--- a/src/dialog_export.cpp
+++ b/src/dialog_export.cpp
@@ -199,14 +199,7 @@ void DialogExport::OnProcess(wxCommandEvent &) {
 		c->ass->Properties.export_encoding = from_wx(charset_list->GetStringSelection());
 		exporter.Export(filename, from_wx(charset_list->GetStringSelection()), &d);
 	}
-	catch (agi::UserCancelException const&) {
-	}
-	catch (const char *error) {
-		wxMessageBox(error, "Error exporting subtitles", wxOK | wxICON_ERROR | wxCENTER, &d);
-	}
-	catch (wxString const& error) {
-		wxMessageBox(error, "Error exporting subtitles", wxOK | wxICON_ERROR | wxCENTER, &d);
-	}
+	catch (agi::UserCancelException const&) { }
 	catch (agi::Exception const& err) {
 		wxMessageBox(to_wx(err.GetMessage()), "Error exporting subtitles", wxOK | wxICON_ERROR | wxCENTER, &d);
 	}
diff --git a/src/ffmpegsource_common.cpp b/src/ffmpegsource_common.cpp
index 1ff0776e9..705c93bd0 100644
--- a/src/ffmpegsource_common.cpp
+++ b/src/ffmpegsource_common.cpp
@@ -69,7 +69,7 @@ FFmpegSourceProvider::FFmpegSourceProvider(agi::BackgroundRunner *br)
 	if (SUCCEEDED(res))
 		COMInited = true;
 	else if (res != RPC_E_CHANGED_MODE)
-		throw "COM initialization failure";
+		throw agi::EnvironmentError("COM initialization failure");
 #endif
 
 	// initialize ffmpegsource
@@ -87,7 +87,6 @@ FFMS_Index *FFmpegSourceProvider::DoIndexing(FFMS_Indexer *Indexer, agi::fs::pat
 	ErrInfo.BufferSize	= sizeof(FFMSErrMsg);
 	ErrInfo.ErrorType	= FFMS_ERROR_SUCCESS;
 	ErrInfo.SubType		= FFMS_ERROR_SUCCESS;
-	std::string MsgString;
 
 	// index all audio tracks
 	FFMS_Index *Index;
@@ -103,11 +102,8 @@ FFMS_Index *FFmpegSourceProvider::DoIndexing(FFMS_Indexer *Indexer, agi::fs::pat
 			nullptr, nullptr, IndexEH, callback, ps, &ErrInfo);
 	});
 
-	if (Index == nullptr) {
-		MsgString += "Failed to index: ";
-		MsgString += ErrInfo.Buffer;
-		throw MsgString;
-	}
+	if (Index == nullptr)
+		throw agi::EnvironmentError(std::string("Failed to index: ") + ErrInfo.Buffer);
 
 	// write index to disk for later use
 	FFMS_WriteIndex(CacheName.string().c_str(), Index, &ErrInfo);
@@ -214,7 +210,6 @@ agi::fs::path FFmpegSourceProvider::GetCacheFilename(agi::fs::path const& filena
 	return result;
 }
 
-/// @brief		Starts the cache cleaner thread
 void FFmpegSourceProvider::CleanCache() {
 	::CleanCache(config::path->Decode("?local/ffms2cache/"),
 		"*.ffindex",
diff --git a/src/fft.cpp b/src/fft.cpp
index 3de4e3a54..82a9af862 100644
--- a/src/fft.cpp
+++ b/src/fft.cpp
@@ -37,12 +37,13 @@
 #include "fft.h"
 
 #ifndef WITH_FFTW3
+#include <libaegisub/exception.h>
+
 #include <cmath>
 
 void FFT::DoTransform (size_t n_samples,float *input,float *output_r,float *output_i,bool inverse) {
-	if (!IsPowerOfTwo(n_samples)) {
-		throw "FFT requires power of two input.";
-	}
+	if (!IsPowerOfTwo(n_samples))
+		agi::InternalError(throw "FFT requires power of two input.");
 
 	// Inverse transform
 	float angle_num = 2.0f * 3.1415926535897932384626433832795f;
diff --git a/src/gl_text.cpp b/src/gl_text.cpp
index 50f83971d..94f866961 100644
--- a/src/gl_text.cpp
+++ b/src/gl_text.cpp
@@ -38,6 +38,7 @@
 #include "utils.h"
 
 #include <libaegisub/color.h>
+#include <libaegisub/exception.h>
 
 #include <wx/bitmap.h>
 #include <wx/dcmemory.h>
@@ -151,7 +152,7 @@ class OpenGLTextTexture final : boost::noncopyable {
 		// Upload image to video memory
 		glBindTexture(GL_TEXTURE_2D, tex);
 		glTexSubImage2D(GL_TEXTURE_2D, 0, x, y, imgw, imgh, GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, &alpha[0]);
-		if (glGetError()) throw "Internal OpenGL text renderer error: Error uploading glyph data to video memory.";
+		if (glGetError()) throw agi::EnvironmentError("Internal OpenGL text renderer error: Error uploading glyph data to video memory.");
 	}
 
 public:
@@ -173,7 +174,7 @@ public:
 
 		// Allocate texture
 		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, width, height, 0, GL_ALPHA, GL_UNSIGNED_BYTE, nullptr);
-		if (glGetError()) throw "Internal OpenGL text renderer error: Could not allocate Text Texture";
+		if (glGetError()) throw agi::EnvironmentError("Internal OpenGL text renderer error: Could not allocate text texture");
 
 		TryToInsert(glyph);
 	}
diff --git a/src/main.cpp b/src/main.cpp
index 2473af282..5ed15e0c0 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -322,14 +322,6 @@ bool AegisubApp::OnInit() {
 		if (!files.empty())
 			frame->context->project->LoadList(files);
 	}
-	catch (const char *err) {
-		wxMessageBox(err, "Fatal error while initializing");
-		return false;
-	}
-	catch (wxString const& err) {
-		wxMessageBox(err, "Fatal error while initializing");
-		return false;
-	}
 	catch (agi::Exception const& e) {
 		wxMessageBox(to_wx(e.GetMessage()), "Fatal error while initializing");
 		return false;
@@ -432,12 +424,6 @@ bool AegisubApp::OnExceptionInMainLoop() {
 	catch (const std::exception &e) {
 		SHOW_EXCEPTION(to_wx(e.what()));
 	}
-	catch (const char *e) {
-		SHOW_EXCEPTION(to_wx(e));
-	}
-	catch (const wxString &e) {
-		SHOW_EXCEPTION(e);
-	}
 	catch (...) {
 		SHOW_EXCEPTION("Unknown error");
 	}
@@ -453,8 +439,6 @@ int AegisubApp::OnRun() {
 		if (m_exitOnFrameDelete == Later) m_exitOnFrameDelete = Yes;
 		return MainLoop();
 	}
-	catch (const wxString &err) { error = from_wx(err); }
-	catch (const char *err) { error = err; }
 	catch (const std::exception &e) { error = std::string("std::exception: ") + e.what(); }
 	catch (const agi::Exception &e) { error = "agi::exception: " + e.GetMessage(); }
 	catch (...) { error = "Program terminated in error."; }
diff --git a/src/subs_controller.cpp b/src/subs_controller.cpp
index ff43a25c9..5aff32e18 100644
--- a/src/subs_controller.cpp
+++ b/src/subs_controller.cpp
@@ -214,7 +214,7 @@ ProjectProperties SubsController::Load(agi::fs::path const& filename, std::strin
 void SubsController::Save(agi::fs::path const& filename, std::string const& encoding) {
 	const SubtitleFormat *writer = SubtitleFormat::GetWriter(filename);
 	if (!writer)
-		throw "Unknown file type.";
+		throw agi::InvalidInputException("Unknown file type.");
 
 	int old_autosaved_commit_id = autosaved_commit_id, old_saved_commit_id = saved_commit_id;
 	try {
diff --git a/src/subtitle_format_ass.cpp b/src/subtitle_format_ass.cpp
index 107884a7b..77184df4e 100644
--- a/src/subtitle_format_ass.cpp
+++ b/src/subtitle_format_ass.cpp
@@ -34,19 +34,12 @@
 DEFINE_EXCEPTION(AssParseError, SubtitleFormatParseError);
 
 void AssSubtitleFormat::ReadFile(AssFile *target, agi::fs::path const& filename, agi::vfr::Framerate const& fps, std::string const& encoding) const {
-	TextFileReader file(filename, encoding);
 	int version = !agi::fs::HasExtension(filename, "ssa");
-	AssParser parser(target, version);
 
-	while (file.HasMoreLines()) {
-		std::string line = file.ReadLineFromFile();
-		try {
-			parser.AddLine(line);
-		}
-		catch (const char *err) {
-			throw AssParseError("Error processing line: " + line + ": " + err);
-		}
-	}
+	TextFileReader file(filename, encoding);
+	AssParser parser(target, version);
+	while (file.HasMoreLines())
+		parser.AddLine(file.ReadLineFromFile());
 }
 
 #ifdef _WIN32
diff --git a/src/subtitles_provider.cpp b/src/subtitles_provider.cpp
index 2c19f73a5..9fc56f8c4 100644
--- a/src/subtitles_provider.cpp
+++ b/src/subtitles_provider.cpp
@@ -60,8 +60,7 @@ std::unique_ptr<SubtitlesProvider> SubtitlesProviderFactory::GetProvider(agi::Ba
 			if (provider) return provider;
 		}
 		catch (agi::UserCancelException const&) { throw; }
-		catch (std::string const& err) { error += factory->name + ": " + err + "\n"; }
-		catch (const char *err) { error += factory->name + ": " + std::string(err) + "\n"; }
+		catch (agi::Exception const& err) { error += factory->name + ": " + err.GetMessage() + "\n"; }
 		catch (...) { error += factory->name + ": Unknown error\n"; }
 	}
 
diff --git a/src/subtitles_provider_libass.cpp b/src/subtitles_provider_libass.cpp
index 183fa236f..0d2bfdd01 100644
--- a/src/subtitles_provider_libass.cpp
+++ b/src/subtitles_provider_libass.cpp
@@ -131,7 +131,7 @@ public:
 	void LoadSubtitles(const char *data, size_t len) override {
 		if (ass_track) ass_free_track(ass_track);
 		ass_track = ass_read_memory(library, const_cast<char *>(data), len, nullptr);
-		if (!ass_track) throw "libass failed to load subtitles.";
+		if (!ass_track) throw agi::InternalError("libass failed to load subtitles.");
 	}
 
 	void DrawSubtitles(VideoFrame &dst, double time) override;
diff --git a/src/video_provider_ffmpegsource.cpp b/src/video_provider_ffmpegsource.cpp
index a3f307bbc..9c8b4cdc5 100644
--- a/src/video_provider_ffmpegsource.cpp
+++ b/src/video_provider_ffmpegsource.cpp
@@ -132,11 +132,8 @@ FFmpegSourceVideoProvider::FFmpegSourceVideoProvider(agi::fs::path const& filena
 
 	LoadVideo(filename, colormatrix);
 }
-catch (std::string const& err) {
-	throw VideoOpenError(err);
-}
-catch (const char * err) {
-	throw VideoOpenError(err);
+catch (agi::EnvironmentError const& err) {
+	throw VideoOpenError(err.GetMessage());
 }
 
 void FFmpegSourceVideoProvider::LoadVideo(agi::fs::path const& filename, std::string const& colormatrix) {
diff --git a/src/video_provider_yuv4mpeg.cpp b/src/video_provider_yuv4mpeg.cpp
index 5694aca9b..6165fe40e 100644
--- a/src/video_provider_yuv4mpeg.cpp
+++ b/src/video_provider_yuv4mpeg.cpp
@@ -402,7 +402,7 @@ std::shared_ptr<VideoFrame> YUV4MPEGVideoProvider::GetFrame(int n) {
 			break;
 		/// @todo add support for more pixel formats
 		default:
-			throw "YUV4MPEG video provider: GetFrame: Unsupported source colorspace";
+			throw VideoNotSupported("YUV4MPEG video provider: GetFrame: Unsupported source colorspace");
 	}
 
 	auto src_y = reinterpret_cast<const unsigned char *>(file.read(seek_table[n], luma_sz + chroma_sz * 2));